San Francisco, CA (SportsNetwork.com) - Rickie Fowler and John Senden won their matches on Thursday and will advance to the round of 16 at the WGC- Cadillac Match Play Championship.

Fowler held off Shane Lowry, 1-up, to clinch his group, while Senden took down Bill Haas, 4 & 3, to clinch his pod. Fowler and Senden could both lose Friday's matches and still advance.

Heading into Friday's play, 18 players have won their first two matches. Joining Fowler and Senden with two victories through two rounds are world No. 1 Rory McIlroy, Masters champion Jordan Spieth, reigning FedExCup champion Billy Horschel, Lee Westwood, Bubba Watson, Louis Oosthuizen, Marc Leishman, Charley Hoffman, Charl Schwartzel, Paul Casey, Gary Woodland, Webb Simpson, Brooks Koepka, Hunter Mahan, Danny Willett and Hideki Matsuyama,

Mahan has played the fewest holes through two days, 27 and has yet to lose a hole.

With that group of 2-0 players, it sets up four matches on Friday pitting two 2-0 players. Among that group: McIlroy faces Horschel, Spieth battles Westwood, Woodland takes on Simpson, and Watson squares off against Oosthuizen in a rematch of their 2012 Masters playoff.

Lowry bogeyed the second to give Fowler a 1-up lead, but Lowry responded with birdies at three and four to move 1-up. They halved seven straight holes before Lowry took the 12th to go 2-up.

However, Lowry stumbled to bogeys at 13 and 14 to square the match. After three halves, Fowler birdied the par-5 18th to seal the 1-up win.

"I had to kind of fight and claw my way back. Shane gave me a couple holes on the back nine, which I needed to really get back into it, and made some great putts coming in," Fowler said. "It's been a long time coming that I've been waiting to make putts like that, since towards the end of last year, so it's nice to see those go in."

Senden bogeyed the second, but came back with a birdie on No. 3 to square things up with Haas. Senden moved 1-up by taking the fourth with a bogey. The pair traded wins at seven and eight.

Haas tripped to a bogey at the ninth to slide 2-down at the turn. The pair traded wins at 10 and 11. Haas dropped shots at 13 and 14 to fall 4-down, and after they matched pars at No. 15, Senden was moving on.

McIlory birdie the first and eighth to move 2-up, but Brandt Snedeker birdied the ninth to make the turn 1-down. After Snedeker bogeyed the 10th, he came right back with birdies at 11 and 12 to square the match. McIlroy reclaimed a 1-up lead as he birdied the 15th.

The reigning Open champion and PGA Championship winner birdied the last to earn a 2-up win.

McIlroy will take on Horschel, who topped Jason Dufner, 3 & 2. Horschel won the first and fourth with birdies, but faltered to a double-bogey at the seventh to lose that hole. He got that back by taking the 10th. Dufner missed a short par putt at 16 to lose the match.

Spieth was 2-down after two holes against Matt Every. After they traded wins at four and five, Spieth won five of seven holes from the sixth to jump 3-up. After matching pars at 13 and 14, Spieth rolled in a 9-footer for birdie and the 4 & 3 win.

"I've been taking a little bit safer lines on my approach shots to get a mid- range putt and feel really good on these greens. They're new greens, which means putts don't break as much," said Spieth, who had 10 straight 1-putts on Thursday. "I really found a rhythm today."

Last year's winner Jason Day and runner-up Victor Dubuisson lost their second straight match and won't advance to the round of 16. Day won just two holes against Branden Grace, who had four birdies and an eagle in the first 12 holes to grab at 3-up lead. Day tripped to a bogey on the 15th to fall 4 & 3.

Dubuisson and Matt Jones traded wins at two and five. Jones took the next three holes before Dubuisson birdied the ninth to make the turn 2-down. After Dubuisson won the 10th with a birdie, Jones bogeyed No. 13 to square the match. Jones birdied 17 and 18 to earn the 2-up win.

These 20 players cannot move to the round of 16: Day, Dubuisson, Dufner, Lowry, Haas, Snedeker, Adam Scott, Henrik Stenson, Ryan Palmer, Brendon Todd, Keegan Bradley, Miguel Angel Jimenez, Jimmy Walker, Ian Poulter, Russell Henley, Harris English, Graeme McDowell, Ryan Moore, Stephen Gallacher and Alexander Levy.

NOTES: After 18 higher-seeded players won on Wednesday, 16 higher-seeded players won their matches on Thursday ... There were seven matches that went extra holes on Thursday, with Tommy Fleetwood topping Jamie Donaldson in 21 holes being the longest match.