The knockout stage at the Dell Match Play started a day early.

The pressure was already cranked up to high Friday in win-or-go-home matches that saw defending champion Rory McIlroy pushed through a 20-hole grinder and Phil Mickelson sent home in a rout.

The round-robin format sent several pairs to the first tee with both players 2-0 and facing elimination with a loss. And none was bigger than McIlroy fighting off Kevin Na in a match that wasn't settled until the second playoff hole.

Mickelson was quickly dismissed by Ryder Cup and Presidents Cup teammate Patrick Reed. The 24-year-old Reed steamrolled the 45-year-old Mickelson by winning six of the first nine holes before closing out the match 5 and 4.

"Today it was either do or die," McIlroy said. "It's a sigh of relief. It's nice to get to the weekend."

McIlroy hasn't lost a match in this tournament in two years, but has had to work hard for his three wins this week. He trailed on the back nine in both of his first two matches before rallying to win Wednesday and Thursday.

Na pushed him again Friday. McIlroy didn't lead the match until No. 15, then lost it one hole later as the duel heated up. They were all square on No. 18 when both stood over short putts for par. Na suggested they pick up and move on. McIlroy said no.

Both made their putts, but McIlroy was determined to test Na under pressure.

"I'm pretty confident over those and I wanted to put as much pressure on him as I could," McIlroy said. "When it's that tight on the last hole, I would rather just hole the putt. At least it gives you a little momentum going into the playoff."

Na, who lost to McIlroy in the first round in 2010, bogeyed the second playoff hole to finally bow out.

There was nothing tense about Reed's dispatching of Mickelson. Mickelson opened the door with a double bogey on the first hole and the rout was on. Reed had two eagles in the first 10 holes.

Reed continues to build an impressive match-play resume. He was a rare bright spot for the U.S. team in the 2014 Ryder Cup when he went 3-0-1 and showed the bravado his teammates lacked when he put his fingers to his lip to "shush" the European home crowd.

Reed brought that kind of confidence against Mickelson. He hasn't trailed in a match yet this week.

"I love match play," Reed said. "I relish every time I get to go in this format and go up against one guy ... just going out and getting in a dog fight."

In other loser-goes-home matches, Matt Kuchar beat Justin Rose 3 and 2, Brandt Snedeker topped Charl Schwartzel 5 and 3, and Louis Oosthuizen beat Andy Sullivan 4 and 2.

Perhaps no match was more entertaining than the duel between Adam Scott and Bill Haas, who were at times sloppy and then brilliant at the end. They didn't halve a hole over the final 11, and there were 13 lead changes.

Scott went 1 up with a birdie on the 16th and had to win the match to advance. Haas made a 12-foot birdie putt to square it on the 17th, meaning Scott had to win the 18th to advance. Haas only needed to halve. They hit their drives in the right rough about 10 yards away from each other. Haas hit his approach to 15 feet, Scott went onto the fringe about 30 feet away with 6 feet of break.

It never came close, and Haas made his putt.

"I struggled all day tee to green," Haas said. "Adam gave me a few holes. Matter of fact, when we shook hands, he said, 'I don't know what to say about that, but you need to play better tomorrow,' which was the truth."