Hunter Mahan and Ian Poulter both won their quarterfinal matches on Saturday to advance to the semifinals at the World Golf Championship - Accenture Match Play Championship.

Mahan, the defending champion and sixth seed in the Gary Player Bracket, ousted reigning U.S. Open winner Webb Simpson, 1-up. Mahan will face Poulter in the semis after Poulter won his match 3 & 2.

Poulter, the third seed in the Sam Snead Bracket, took down fourth-seeded Steve Stricker, the 2001 champion. Poulter, who is now 22-9 all time at this event, is the highest remaining seed.

The other semifinal at The Golf Club at Dove Mountain will pit Matt Kuchar against Jason Day. Kuchar, the sixth seed in the Ben Hogan Bracket, beat fellow American Robert Garrigus, 3 & 2.

Day, the 11th seed in the Bobby Jones Bracket, held off former U.S. Open winner Graeme McDowell, 1-up.

Mahan and Simpson were in a battle throughout. Mahan birdied the fifth to grab a 1-up lead, but Simpson got up and down for birdie at eight to square the match.

At the 10th, Mahan rolled in about a 30-footer for birdie and a 1-up lead. Simpson again squared things with a 6-foot birdie putt at 13. Mahan reclaimed the lead with a par on 16. The duo halved the final two holes with pars to give Mahan his 10th straight match win at this championship.

"It's like a final round in each match, especially right now, when you get closer and closer (to the end). It's exciting at the same time," Mahan said in a televised interview.

Stricker, the 2001 winner, took the first with a 20-foot birdie putt, but it was all Poulter the rest of the front nine. Poulter got up and down for birdie at two, then made a huge right-to-left breaking putt at the third to take a 1- up lead.

Poulter, the 2010 champ, chipped in for birdie at six and ran home a 25-footer for eagle at the eighth to push his lead to 3-up. Stricker got one back with a short birdie putt at 10, but Poulter was conceded the 11th and birdied the 12th to extend his margin to 4-up.

Stricker, who celebrated his 46th birthday on Saturday, was conceded the 14th, but after they halved the next two holes, Poulter moved on.

"I tell you I've got a lot of (confidence) I think. I feel comfortable in this format," Poulter said in a TV interview. "I've got a good record and that continues."

Kuchar, the sixth seed in the Ben Hogan Bracket, won the first and third with pars, then stumbled to a bogey on the fourth as his lead dipped to 1-up. He pushed that back to 2-up with a 6-foot birdie putt at the sixth.

At the ninth, Kuchar rolled in a birdie effort to win the hole. He was conceded his par putt at the 10th as Garrigus made a mess of the whole.

Garrigus took the 12th when Kuchar 3-putted for bogey, then Garrigus birdied the 13th to get back within 2-down. Kuchar converted a 3-foot birdie effort at 15. They matched pars at No. 16 and the match was Kuchar's.

"It's nice to be still alive and playing tomorrow. Robert today gave me a couple holes early. I got off to a nice lead and then I stumbled a little bit there kind of three-quarters into the round and kind of felt like we were back in a battle again," Kuchar stated. "I was pretty excited to hit some good shots on 14, 15 and 16 to be able to close him out and be able to hopefully go home soon and get some rest."

Day quickly fell 2-down as he conceded McDowell's birdie at one, then McDowell rolled in an 18-footer at the third. Day took the fourth with a par, then sank an 8-foot par save at seven to square the match.

After three straight halves, Day sank a 4-footer for birdie at 11 to go 1-up. The duo traded birdies at 14 and 15. McDowell parred 16 to again square the match, but Day 2-putted for par on 17 to regain a 1-up lead.

At the last, Day had about 40 feet for birdie and rolled that inside three feet. McDowell 2-putted for par from the back fringe, before Day tapped in for par to close out the victory.

"We played a lot of holes today, so I've got to make sure I get some rest tonight. I know it's going to be just as stressful," Day said in a TV interview. "It's like Sunday every day here."

NOTES: Kuchar and Mahan are trying to extend a streak in which every PGA Tour winner this year has been American ... Mahan is the first reigning champion to make the semifinals since 2007 winner Geoff Ogilvy did it in 2008 ... Along with Poulter's 22-9 record, all four semifinalists have winning records at this event -- Mahan (14-4), Kuchar (13-3) and Day (7-2) ... Earlier Saturday, the start of the third round was delayed 45 minutes by frost.