Rory McIlroy produced a stunning back nine comeback to beat Hunter Mahan by two holes but Tiger Woods failed to keep his third round date with the Holywood sensation as he lost to Tim Clark in the Accenture Match Play Championship in Tucson.

Playing his first event after eight months on the sidelines following knee surgery, the world number one went down by 4 and 2 to the gutsy South Africa as McIlroy rallied from two down with six to play to beat Ryder Cup star Hunter Mahan with a stunning birdie-par-birdie-birdie finish.

Asked about missing out on his "dream" showdown with Woods, McIlroy said: "It is probably a good thing. I would probably be the first to say that if I stood on the first tee with Tiger Woods I would be intimidated. He has been a hero of mine for the past I don't know how many years.

"But Tim obviously had to play great to beat the world number one. He has done that today and it will be a tough match.

"I've met Tiger a few times before and he said well done to me on the range about yesterday's match and my first win in Dubai. It would have been great to play him by maybe another time."

McIlroy squared the match at the 14th where Mahan three-putted from 37 feet and after halves at the 15th and 16th, the Ulsterman edged ahead for the first time in the match at the 17th.

The 19-year-old found a fairway bunker off the tee but with the Texan driving into the desert, he fired a 150 yard beauty to 12 feet and rolled home the birdie putt to get his nose in front

Then at the last McIlroy hit a three wood off the tee, drilled a five iron to 18 feet and drained the putt to secure a minimum payout of $140,000.

delighted with his performance, McIlroy said: "It was a tough match out there today and Hunter is a great player. He was missing greens and getting up and down. He wouldn't go away and got two up on me and I really had to dig deep.

"I played my best golf when I needed to and that was very satisfying.  You have to really concentrate and play every shot as if it were your last and I did that today."

Golf fans have been licking its lips all week at the prospect of a mouth-watering showdown between the king of golf and Ireland’s crown prince.

But Woods path to the third round was blocked by the doughty South African Clark in the spectacular Sonoran desert, 20 miles north of Tucson.

Playing solid but unspectacular golf, Woods trailed a sensational Clark by three holes with five to play before holing a 55-foot bunker shot to win the 14th in birdie and reduce the deficit to two down with four remaining.

And it was even tighter for McIlroy who birdied the par-five 13th to get back to just one down to US Ryder Cup star Mahan with five to play in a game that was lacking in quality but high on emotion.

That dream was evaporating in the searing afternoon sun as the 28 year old Texan took advantage of every opening to forge a two hole cushion after 12 holes.

But it was the performance of Clark that drew the most interest as he played David to Woods’ Goliath.

Back in action after an eight month lay-off following knee surgery, Woods looked likely to dominate from the moment he hit an amazing 286-yard hook with a three wood to 28 feet and two-putted for the win to go one up.

But Clark hit back to level the match at the sixth by holing an incredible 68-foot putt and then edged one up at the short sixth, where Woods was plugged in a greenside trap and bogeyed.

The American superstar showed his class by bouncing back straight away with a winning birdie three from just seven feet to square the match again.

Yet while they halved the eighth in birdie fours,  Clark took advantage of a wayward Woods drive at the par-five 11th to win that hole with a birdie and go one up before hitting a stunning iron to seven feet at the short 12th to double his advantage to two holes.

At the par five 13th, Clark showed that accuracy trumps power every time when he hit a great three wood into the green and made a two putt birdie and Woods lipped out with a 10 footer to go three down with five to play.

But Woods responded holing a bunker shot for a winning birdie at the 14th to give the South African food for thought over the closing holes.

In the end, though, there would be no miracle comeback by the America and his tournament effectively ended at the driveable 15th, when he drove through the green and out of bounds.

Still, there was drama.

Woods refused a cart ride back to the tee, 345 yards away, in a ploy designed to make Clark think long and hard about his 60 yard second shot from a fairway bunker.

And when Woods hit a stunning third from the tee to 20 feet, he still had a chance to make four and hope that Clark would somehow make a massive error.

But the South African splashed out to 18 feet behind the pin and when Woods missed his par putt, he two-putted for a winning par to go three up with three to play.

It all ended at the short 16th, where Clark his tee shot to four and a half feet. Woods missed the green, failed to chip in and shook hands with a player who has yet to make a bogey in the championship.

McIlroy was just as impressive in his clash with Mahan, who didn’t set the course alight but put the Ulster kid under serious pressure with his short game skills.

At the first, McIlroy had a chance to go one up when Mahan drove into trouble off the tee. But he missed the green and failed to make his par four.

The second was halved in nervy par fives after both men missed the fairway but it was the American Ryder Cup star who drew first blood when he got up and down from sand for a winning par at the short third.

McIlroy levelled things with a birdie three at the fourth, where he hit a wedge to eight feet before they halved the next three holes in par to remain all square with 11 to play.

But Mahan surged ahead, winning the eighth with a birdie five to go one up and then doubling his advantage at the 12th with an incredible approach that finished just 15 inches from the hole.

McIlroy’s power gave him the 14th with a two-putt birdie and after sharing the 15th in birdie threes, the Ulster sensation saved half with a chip to inches at the par three 16th before polishing off his opponent with those closing birdies.

If McIlroy beats Clark, he will play the winner of the clash between Camilo Villegas and Geoff Ogilvy in Saturday morning's quarter-finals.

The Colombia had seven birdies as he hammered Miguel Angel Jimenez 5 and 4 as 2006 champion Ogilvy came back from two down with two to play to beat Shingo Katayama at the 19th.

Luke Donald beat Vijay Singh at the 19th to set up a meeting with Ernie Els while world No 3 Phil Mickelson was the first man to book his place in the last 16 thanks to a nervy, one-up victory over Zach Johnson that set up a meeting with Stewart Cink, who beat Lee Westwood at the 23rd.

In the other half of the draw, Ian Poulter beat Charl Schwartzel and now faces Sean O'Hair, who beat Boo Weekley. Peter Hanson will take on Paul Casey and Ross Fisher will meet Jim Furyk after they saw off Pat Perez and Martin Kaymer respectively.

The biggest surprise of the day for many was the 2 and 1 defeat of golden boy Anthony Kim at the hands of European Ryder Cup player Oliver Wilson.

Still looking for his first tour win, Wilson had six birdies in an ten-hole stretch from the eighth and eight birdies overall in an impressive victory that pits him against Justin Leonard, who was a one-up winner over Davis Love.