Kaymer let a big lead slip away on the back nine on Saturday morning of the Match Play Championship before parring the 18th hole to defeat Miguel Angel Jimenez of Spain.

Kaymer would replace Lee Westwood at No. 1 if he reaches the final at Dove Mountain.

Kaymer plays the winner of the J.B. Holmes-Bubba Watson match. Holmes has a 1-up lead playing the long 18th hole.

Britain’s Luke Donald became the first player to reach the semifinals of the WGC-Accenture Match Play Championship with a commanding 5&4 victory over American Ryan Moore on Saturday.

The Englishman produced sparkling form on a chilly, overcast morning at Dove Mountain’s Ritz-Carlton Golf Club, compiling seven birdies and just one bogey to overpower his opponent.

Donald, who beat Italian teenager Matteo Manassero 3&2 in the third round, was four up at the turn and sank a nine-foot birdie putt at the par-four 14th to seal the win.

“I played nicely today,” world number nine Donald said greenside. “Every match, I’ve gotten off to a good start. I’ve gotten up early and kept my nose ahead.” Moore, who was level par after 14 holes, applauded Donald’s display.

“He played great,” the American told reporters. “I knew I had to play well against him and I just made him a little too comfortable.

“I didn’t put too much pressure on him early on. You can’t give holes away. I did that a couple of times early and let him pad his lead and from there I think he just cruised.” Donald, who would climb to a career-high third in the world rankings by winning this week’s final, will next meet either American Matt Kuchar or South Korean Yang Yong-eun.

United States Ryder Cup player Kuchar was two up on 2009 PGA Championship winner Yang with four holes to play.

In the other quarterfinal matches, Germany’s world number two Martin Kaymer was three up on Spaniard Miguel Angel Jimenez after 13 holes and J.B. Holmes was four up on fellow American Bubba Watson after 12 holes.

The 18-hole championship final is scheduled for Sunday, when showers and possible snow flurries are expected.