Defending champion Hunter Mahan earned a 4 & 3 win over Richard Sterne on Friday to move on to the third round at the World Golf Championship - Accenture Match Play Championship.
Mahan, the sixth seed in the Gary Player Bracket, will face 2011 runner-up Martin Kaymer in round three.
While they moved on, the two remaining No. 1 seeds were both ousted on Friday. Scott Piercy rolled to a 7 & 6 win over Luke Donald, while Robert Garrigus toppled Louis Oosthuizen, 3 & 2, at The Golf Club at Dove Mountain.
Mahan and Sterne were even at the turn, but Mahan won four in a row to take control. The pair both parred the next two holes to seal Mahan's win.
"I enjoy playing this golf course," Mahan said in a televised interview. I just feel comfortable on each shot. I've got a good rhythm here,"
Kaymer won three holes in a 5-hole span to go 3-up in his match with Rafael Cabrera Bello, who got one back at 13 before the two halved four straight to give Kaymer the 2 & 1 win.
In the top portion of that bracket, Gonzalo Fernandez-Castano knocked out Charles Howell III, who beat Tiger Woods in the first round. The Spaniard won back-to-back holes from the first and again from the seventh. Fernandez- Castano later birdied Nos. 11 and 13 to close out the 6 & 5 win.
Fernandez-Castano will face U.S. Open champ Webb Simpson, who birdied the 18th to beat Peter Hanson, 1-up. Simpson never led until winning the last hole.
Piercy was 6-under par through nine holes with four birdies and an eagle, and led Donald, 6-up. He later birdied the 12th to seal the big win.
Piercy will face Steve Stricker, who needed 21 holes to oust fellow American Nick Watney. Stricker, the 2001 champion, twice lost a 2-up lead as Watney birdied the 17th to even the match. Stricker then missed a 3-footer for birdie and the win at 18, but Watney made a mess of the 21st and conceded the match.
The bottom part of that bracket has 15th-seeded Tim Clark facing Ian Poulter. Clark bested Thorbjorn Olesen, 3 & 2, while Poulter beat Bo Van Pelt, 3 & 1.
Clark was 3-up after 10, but Olesen birdied the 12th. Clark birdied the 14th to regain a 3-up lead and the match was over after a pair of pars.
Poulter, the third seed, won five of six holes from the sixth to take control of the match. Van Pelt tried to fight back with birdies at 12 and 13, but Poulter -- the 2010 champion -- was conceded birdie and the match at 17.
"It's feeling pretty good, I must say," Poulter said on TV. It was a little risky taking six weeks off before coming into this week, but it's worked out very well. I've done a bunch of great work at home, and I couldn't feel fresher or fitter than I do now."
Garrigus, the ninth seed in the Ben Hogan Bracket, took the ninth with a birdie and the 10th with a par. He birdied No. 13 to push his lead to 3-up, then he and Oosthuizen halved the next three and the match was over.
Garrigus will face Fredrik Jacobson, a 4 & 3 winner over Marcus Fraser. Jacobson took the first two holes, then birdied the eighth to move 3-up. Jacobson birdied No. 15 to close out the match.
The bottom half of that bracket has 10th-seeded Nicolas Colsaerts taking on Matt Kuchar. They faced each other in a four-ball match at the 2012 Ryder Cup.
Colsaerts ran off three straight wins from the fifth to go 3-up on Justin Rose, who managed to get back within 1-down after an eagle on the 12th. Colsaerts won three of the next five holes to close out the 4 & 2 win.
Kuchar, the sixth seed, had a tough battle with Sergio Garcia. They halved nine of the first 13 holes while trading wins on the other four. Kuchar converted a birdie try at 14 to go 1-up. The pair birdied the 15th and parred No. 16, but Kuchar birdied the 17th from inside three feet to seal the win.
Shane Lowry, who beat Rory McIlroy in round one, kept rolling by cruising to a 6 & 5 win over Carl Pettersson. Lowry won three of four holes from the sixth, and back-to-back wins at 12 and 13 sealed the win.
"I struggled to get to sleep last night," said Lowry in a TV interview. I know Carl's a great player and great putter, and I knew it was going to be quite difficult. I played solid all day. I made a few birdies and didn't do anything wrong, which is key in match play."
Lowry will take on another Northern Irishman in Graeme McDowell after the fifth seed needed 20 holes to beat Alexander Noren. McDowell led 1-up three times, while Noren was 1-up twice in their see-saw match.
Noren hit into a bush with his second on the 20th hole, but got a drop from a TV tower. He struggled to a bogey and conceded McDowell's birdie try and the match.
The final match will put Bubba Watson against Jason Day. Jim Furyk birdied the 18th from just over four feet out, while Watson missed from inches closer to force extra holes. Watson finally won on the 22nd hole.
Day was 1-down to Russell Henley after 11 holes, but won three in a row from the 12th. Henley fought back to force extra holes with a birdie at 18. Day then birdied the 19th for the win.
NOTES: The tournament remains behind schedule after snow stopped play on Wednesday ... The third round and quarterfinals are slated for Saturday, and if they are completed that day, the championship will be back on schedule ... Mahan is the first defending champion to make it past the second round since 2007 winner Geoff Ogilvy reached the 2008 semifinals ... The last time all four top seeds failed to make the third round was 2010 ... Clark was the lowest ranked of the seven South Africans in the championship, but is the only remaining after two rounds.