Rory McIlroy of Northern Ireland plays a shot from the rough on the fifteenth hole during Day Two of The 150th Open at St Andrews Old Course on July 15, 2022 in St Andrews, Scotland. (Photo by Stuart Kerr/R&A/R&A via Getty Images)

Rory McIlroy took a leaf out of the Dr Bob Rotella book of mental golf and insisted he just has to play his normal game to chase down leader Cameron Smith and claim his second Claret Jug on Sunday.

The Holywood star was four shots adrift of the Australian with three holes to go but made a key par save at the 16th, then made just the fifth birdie of the day at the 17th en route to a 68 that leaves him just three shots behind, tied for third with Viktor Hovland on 10-under.

"I know I've got the game and that's all I need," McIlroy said. "I just need to go out and play my golf over the next two days and that's all I can do.

"If Cam Smith goes out and shoots another two rounds like he did the first two days I am going to have a really hard time to win the tournament. I just have to go out and do the best I can and hopefully that's good enough. I will just try to keep hitting good golf shots until I run out of holes."

Smith knocked in putt after putt as he fired an eight-under 64, starting with a 50-footer for the first of six birdies in the first 10 holes before rolling in a 64-footer for eagle at the 14th.

He leads by two shots from overnight leader Cameron Young (70) on 13-under -- a record 36-hole total for an Open at St Andrews. But McIlroy looks to have another gear and while he started slowly, he birdied the fifth and seventh, then followed a three-putt bogey at the eighth with three birdies in a row from the 10th. He would three-putt again from 100 feet at the 15th to fall four behind but saved par from six feet at the 16th, then ripped a 190-yard approach to 25 feet at the 17th and rolled in the putt to a massive roar.

"The 16th and 17th were important after the bogey on 15," McIlroy said. "To make a nice par save on 16 and birdie 17 was a nice little turning point in the round. It would have been nice to follow up with a birdie at the last but that was big because I didn't want to make two bogeys in a row and to follow that up with a three I felt like I saved a couple of shots there."

As for tipping his hat to Tiger Woods as he crossed the Swilcan Bridge, he said: "We all want to see him do well. He was all our hero growing up and we want to see him still out there competing. This was a tough week for him but we are all behind him and pulling for him and hopefully he his back here in another four or five years and playing another Open Championship around the Old Course."

Shane Lowry birdied the fifth, ninth, 10th and 12th to get to four-under, double-bogeyed the 16th after missing the fairway and taking two to extricate himself from a bad lie in a deep greenside bunker. But he finished with two birdies for a 68 that leaves him nine shots off the lead.

"Overall I am pretty happy but I could have shot something in the mid sixties today," Lowry said. "I holed two nice putts at the end but other than that I felt like I hit some good putts and didn't hole much.

"Sixteen was a kick in the stones. I probably should have laid back off the tee and hit six-iron in and played to my strengths but it is what it is. That's coulda, woulda, shoulda and I finished nicely. I'm happy I did that and I'll be able to watch the match in the morning.

"I probably need to shoot something in the mid-sixties tomorrow. I am trying but it's hard to get going. I didn't birdie 14 and hit two great shots and didn't birdie 15. Then I double 16 and it's like, jeez, I'm one bad swing away from missing the cut here.

"I do feel like I'm in control of my game but I need to hole a few more putts. You can't chase but if I find myself five-under after nine tomorrow, great. It can be done out here."

Open debutant Seamus Power admitted he never got any momentum going as he followed his opening 73 and 75 to miss the cut on four-over.

"I just didn't play really well, to be honest, that's about it," said Power who got to one-under through 11 holes on Thursday but never recovered from a double-bogey at the 12th. "I definitely never got comfortable."

He got a close-up view of leader Smith over the two rounds, watching him hole putt after putt. Can he see Smith lifting the Claret Jug?

"I could, very much so," he said. "That was the most impressive two putting rounds I've seen. I don't know what his footage would have been today. But yeah, it was amazing. Even the putts that he doesn't make, a lot of them look like they're scaring the hole, even from all sorts of distances. His speed is down. He's an aggressive putter, bouncing off the back of the hole."

Meanwhile, Galway's Ronan Mullarney shot 78 to finish on seven-over with 2011 champion Darren Clarke 10-over after a 75.