Shane Lowry is predictably unpredictable, but if you were to pick a course where he might show a scintilla of form after going into semi-hibernation following last year's US Open, it's the West Course at Wentworth.

A four under 68 that saw him give back two early birdies before coming home in four under, left Lowry smiling and determined to repeat the trick today as he seeks to halt his slide down the world rankings by contending for his first win since the 2015 Bridgestone Invitational.

Had his putter been truly hot, he might have matched leader Johan Carlson of Sweden, who shot a 66 to lead by one from Scotland's Scott Jamieson, Thailand's Kiradech Aphibarnrat and Italy's Francesco Molinari.

But Lowry wasn't complaining too much and when asked what happened to him since he came second in the US Open at Oakmont last year, it's clear he was devastated rather than delighted by his best major finish.

"To be honest, if I knew that -- I don't know. I don't know," he said if his lacklustre form since Oakmont was a hangover from not converting the 54-hole lead there into a major win. 

"Obviously I was quite disappointed. It's not easy, I suppose you go into the next major, saying you went to the British Open and PGA and people are talking about you winning, and I've never had that before. It's just not easy. And then obviously The Ryder Cup, was trying to make that and didn't do that.

"So all in all, I was pretty disappointed with how it ended up last year, but look, that's behind me now. We're here this year and I've obviously not played that much this year, and when I've played, it's been a bit rusty I feel.

"I have a great run of tournaments coming up over the summer, so looking forward to doing well and trying to get up that FedExCup and Race to Dubai and back up the World Rankings and back to where I feel I belong, I suppose."

Set for The Memorial at Muirfield Village next week before a quick trip home and the build-up to the US Open, he said he's seen pictures of Erin Hills - a Stateside version of the Montgomerie at Carton House.

"Be interesting," he said. "I'm hoping the rough isn't as long as it looks in the photos. Yeah, I mean, we just have to see when we get there. I hope it's nice. I personally don't like when they try and make inland links golf courses, but listen, that's the course we're at and we'll have to go there and try and do a good job."

Asked what he learned from the US Open last year, it's clear that it's still painful.

"Don't know. To be honest. I've talked about it that much over the last year. Didn't win. End of story. I finished second. It was a great week. I showed that I can win and I showed that I'm as good as anyone.

"That's what I had to take out of it. Obviously, I didn't do a great job in taking the positives out of it the end of last year, but look, that's all behind me now. I feel like I'm playing good golf.

"But to be honest, I feel like I'm doing everything I can to play good golf and that's all I can do. I'm going out every day on the golf course and every day on the range and giving it my best and that's all I can do."

As for the rest of the Irish, Paul Dunne made four birdies in a one-under 71 that leaves him tied 31st.

Pádraig Harrington, back in action after his 12-week layoff following a neck operation, showed signs of obvious rust but still managed a one-over 73 for a share of 61st with Darren Clarke.

As for the Irish PGA professionals, Damien McGrane is 85th after a 74 with the injured Neil O'Briain well down the field after an 82.

Leader Carlsson took advantage of the immaculate new greens at Wentworth Club as he made eight birdies in an impressive six under par round of 66.

Carlsson made a blistering start to the European Tour’s new Rolex Series, reaching the turn in just 30 shots courtesy of five birdies on the front nine, and he picked up three more shots on way in, although his back nine was bookended by bogeys on the tenth and 18th holes.

“It was fun today,” he said. “It’s a big event this year, and you kind of feel it with the atmosphere. Everything is big around this tournament, and obviously, you want to do good.

“The greens are so good. I love this golf course right now.  I think it has become so much better, and I think a lot of other players probably agree with me, as well, on that point.

Carlsson holds a one-shot advantage over Molinari, Jamieson and  Aphibarnrat, while Carlsson’s compatriot Henrik Stenson, the Open Champion, is one of nine players a further shot back on four under par after a bogey-free 68, with all four of his birdies arriving on the back nine.

England’s Ross Fisher andLowry, both of whom have previously finished runner-up in the BMW PGA Championship, are also amongst that group, along with Ryder Cup player Thomas Pieters who bogeyed the closing hole.

A crowd of 20,692 people – the second largest Thursday crowd in the event’s history – watched the opening round and they were treated to innovations including a new entertaining first tee experience.

Johan Carlsson:

“It was fun most of all I would say. You know, it's a big event this year, and you kind of feel it a little bit, the atmosphere. Everything is big around this tournament and obviously, you want to do good.

“I had one goal in mind today, and that was to commit to every shot, as good as I possibly can, and I think I did.

“I started really well today. I felt quite good going into the tournament, and mostly mentally I felt like I was quite well prepared. Got off to a good start and managed just to keep it going. It was just one of those days when you drain a few putts and things kind of go your way, so it's fun.

“I didn't try to hit any super fancy shots. I just played with what I had and I think that was the key to success.

Francesco Molinari:

“The first is always a tough opening hole. I wasn't too pleased with the bogey but you can easily make more there. It's a tough start, one, two and three, and I think if you get around there one-over par, you're still doing okay.

“I played nicely. It wasn't my best maybe, to be honest but I saved a few important shots, and took the opportunities when I had them. Obviously very pleased with five-under, it's a very good start.

“Obviously they got rid of a few bunkers off the tee which makes it a bit more forgiving but if you hit the ball where the bunkers were, you still have a tough shot. So there's a bit more of shot-making involved. I think it's probably more enjoyable for the fans, as well, not to see us just chip it out of the bunker. So I think they made some really good changes.

Scott Jamieson:

“Bogey-free round which is great here at Wentworth. Obviously, we had the best of the conditions, not a breath of air, and the greens are so good this year. To be the first people on all 18 greens, they are just a great surface to putt on.

“I think they have just done such a fantastic job. There's a real premium on hitting the fairways because the greens are firmer. You know, if you're not hitting the fairways, you've then got to think very hard about where you want your next shot to go because it's really difficult to get it on the green with a kind of mid-iron. 

“We're coming into the real thick of it now obviously the Rolex Series. There's a lot of points to play for. I think it makes those tournaments a little easier if you know your job's secure.

“I think the wind is maybe to blow a bit the next couple days, which will probably firm the golf course up a bit, as well and make it that bit trickier.

Kiradech Aphibarnrat:

“I'm really happy with the way I'm playing and the way we started the first round tied for the lead. Still a lot of golf to go.

“The golf course looks fantastic. A lot of bunkers have been taken off making the fairway look a little bit wide but the greens are really firm and fast. It’s still really tough course but it's in great condition out there. Just keep focus on the game, stay patient and play to the course.

Henrik Stenson:

“I didn’t quite get going, I had to scramble a bit for par and from six onwards I played really solid, I gave myself loads of chances. I put in a couple of iron shots that should have been stone dead but when the greens are new they release a bit more and it’s hard to judge that perfectly.

“I left myself with some nice chances and from 11 onwards I picked up some birdies and didn’t drop a shot so it was a solid start.

“I think it’s a very nice surface to putt on out there  but the first year before everything settles in there are a lot of little breaks and I had a hard time finding the right lines early on but I got a couple in on the back nine and kept it pretty tidy.”

First Round Scores:

Detailed scores

66 J Carlsson (Swe), 

67 S Jamieson (Sco), K Aphibarnrat (Tha), F Molinari (Ita), 

68 Shane Lowry (Irl), N Bertasio (Ita), T Pieters (Bel), R Fisher (Eng), B Dredge (Wal), G Storm (Eng), B Grace (RSA), H Stenson (Swe), A Noren (Swe), 

69 D Burmester (RSA), R Ramsay (Sco), E De La Riva (Esp), T Hatton (Eng), R Sterne (RSA), L Haotong (Chn), 

70 A Dodt (Aus), L Westwood (Eng), P Hanson (Swe), O Fisher (Eng), M Kieffer (Ger), F Fritsch (Ger), M Ilonen (Fin), B An (Kor), D Brooks (Eng), A Björk (Swe), J Wang (Kor), 

71 J Luiten (Ned), S Hend (Aus), M Fraser (Aus), B Wiesberger (Aut), A Sullivan (Eng), P Larrazábal (Esp), Paul Dunne (Irl), S Kjeldsen (Den), B Ritthammer (Ger), A Levy (Fra), E Els (RSA), S Gros (Fra), J Van Zyl (RSA), B Hebert (Fra), D Howell (Eng), D Horsey (Eng), A Knappe (Ger), R Karlberg (Swe), N Colsaerts (Bel), N Fasth (Swe) 

72 P Lawrie (Sco), T Jaidee (Tha), J Rose (Eng), G Bourdy (Fra), R Jacquelin (Fra), J Campillo (Esp), D Willett (Eng), J Smith (Eng), T Fleetwood (Eng), C Wood (Eng), 

73 G Havret (Fra), D Lipsky (USA), M Cort (Eng), L Slattery (Eng), P Waring (Eng), Pádraig Harrington (Irl), J Donaldson (Wal), R Wattel (Fra), S Chawrasia (Ind), A Otaegui (Esp), R Knox (Sco), A Johnston (Eng), M Fitzpatrick (Eng), L Jensen (Den), J Morrison (Eng), V Dubuisson (Fra), T Aiken (RSA), M Manassero (Ita), L Bjerregaard (Den), S Gallacher (Sco), S Lee (Kor), A Wall (Eng), Darren Clarke (Nir), G Coetzee (RSA), 

74 S Dyson (Eng), F Aguilar (Chi), D Fichardt (RSA), P Uihlein (USA), W Ormsby (Aus), A Quiros (Esp), M Siem (Ger), M Southgate (Eng), M Pavon (Fra), R Fox (Nzl), R Gouveia (Por), P Peterson (USA), C Pigem (Esp), Damien McGrane (Irl), 

75 L Donald (Eng), J Scrivener (Aus), R Paratore (Ita), T Bjørn (Den), G Hutcheon (Sco), J Lagergren (Swe), D Drysdale (Sco), R Rock (Eng), M Lorenzo-Vera (Fra), F Zanotti (Par), K Broberg (Swe), P Angles (Esp), N Elvira (Esp), M Warren (Sco), P Khongwatmai (Tha), G Fox (Sco), M Korhonen (Fin), 

76 H Tanihara (Jpn), R Langasque (Fra), Z Lombard (RSA), M Wallace (Eng), P Edberg (Swe), T Immelman (RSA), B Stone (RSA), H Otto (RSA), J Walters (RSA), I Poulter (Eng), P Archer (Eng), M Kaymer (Ger), R Karlsson (Swe), C Gane (Eng), H Porteous (RSA), R Bland (Eng), 

77 R Coles (Eng), C Hanson (Eng), E Molinari (Ita), M Carlsson (Swe), J Quesne (Fra), P Streeter (Eng), D Frittelli (RSA), 

78 C Shinkwin (Eng), G Stal (Fra), A Cañizares (Esp), P Hendriksen (Eng), T Olesen (Den), 

79 C Paisley (Eng), D Im (USA), 

80 S Brazel (Aus), 

81 S Walker (Eng), 

82 Neil O'Briain (Irl), 

83 B Rumford (Aus), 

** N Holman (Aus),