Arizona: With the chance to become world number one for the first time, Rory McIlroy is on his guard about a possible emotional letdown should he win his much anticipated semi-final on Sunday against Lee Westwood.

World number two McIlroy will take on third-ranked Westwood in the last four of the WGC-Accenture Match Play Championship in the morning at Dove Mountain where the winner will then contest the 18-hole final on Sunday afternoon.

Should either Northern Irishman McIlroy or Englishman Westwood go on to claim a maiden World Golf Championships (WGC) title, Luke Donald would be deposed as the game's top-ranked player.

"That will be the tough task because both of us have to get past each other, for Lee to get back to number one and me to get there for the first time," McIlroy said after winning his quarter-final 3&2 against South Korean Bae Sang-moon.

"You have to put your all into that (semi-final) and then whoever wins tomorrow morning, you have to get yourself back up again to go back out tomorrow afternoon and win the whole thing."

Should the 22-year-old McIlroy clinch the title on Sunday, he would shatter Tiger Woods' record as the event's youngest winner, the American having triumphed in 2003 at the age of 27.

He would also become the second-youngest player, behind Woods, to reach the top of the world rankings.

However McIlroy knows he faces a tough challenge on Sunday against Westwood, a 21-times winner on the European Tour who deposed Woods as world number one in November 2010.

"The way Lee plays, you know he's going to hit fairways, he's going to hit greens and he's going to put you under pressure the whole day," the Northern Irishman said.

"He's not going to take his foot off the pedal. He's not going to give you any holes, so you have to play the exact same way. And I think tomorrow it'll just come down to who holes the most putts."


While McIlroy won his first major title in scintillating style at last year's U.S. Open, the fact that he has not yet risen to the top of the games rankings may weigh on him on Sunday, according to Westwood.

"I've been at number one a couple of times so it would be a different way of thinking to me compared to Rory who hasn't been number one," Westwood said after beating fellow Briton Martin Laird 4&2.

"He may be thinking about it, but my main goal is to play well, or play as well as I've been playing, tomorrow morning and try to win that match.

"One of us will have a chance to get to the final and win the tournament. That's my main priority."

By advancing into the last four at Dove Mountain, Westwood becomes the fourth Englishman to reach that stage at the event in as many years, following Luke Donald (2011), Ian Poulter (2010) and Paul Casey (2010 and 2009).

Uppermost in his mind is the chance to claim his first crown in a WGC event, which bring together the world's best players are just one rung down from the majors.

"My priorities this year were to win major championships and World Golf Championships because I haven't ever won any," the 38-year-old Englishman said.

"You want to win the big tournaments where the best players are playing, and I've given myself a great chance early in the year to do that."