AUSTIN, Texas — Defending champion Jason Day lasted only six holes at the Dell Technologies Match Play until a heavy heart forced an early departure.

Rory McIlroy and Jordan Spieth might not be far behind.

The opening round of golf’s most unpredictable tournament took a stunning turn Wednesday when the third-seeded Day abruptly conceded his match to Pat Perez, then wiped away tears as he revealed his mother has lung cancer. Day withdrew to be with her in Ohio for surgery on Friday.

“It’s been a very, very hard time for me to even be thinking about playing golf,” Day said. “And I know my mom says not to let it get to me, but it really has. So I just need some time away with her to make sure that everything goes well because this has been very, very tough for me. So I’m going to do my best and try and be there the best I can for her because she is the reason that I’m playing golf today.”

Dustin Johnson had no trouble in his debut as the No. 1 seed. He had five birdies in his opening eight holes at Austin Country Club and there wasn’t much Webb Simpson could do, but try to extend the match as long as he could. It lasted 15 holes in a 5-and-3 victory.

“Got a long way to go, but getting the first match in the books with a win is definitely a head start,” said Johnson, who is trying to win his third straight tournament.

McIlroy (No. 2) and Spieth (No. 5) face critical matches the rest of the way.

McIlroy, the 2015 champion and a semifinalist last year, appeared to seize control against Soren Kjeldsen when he won three straight holes to take the lead, including a 410-yard drive on the par-5 12th hole and another drive over the water to the edge of the green on the 317-yard 13th hole into the wind.

Kjeldsen, crisp as ever with his short irons, ran off four straight birdies to end the match. He took a 1-up lead with a wedge in tight on the par-5 16th, and then his pitching wedge that landed inches from the cup and settled 2 feet away for a birdie on the 17th to end it. Kjeldsen was 6 under on the round.

It was the first time McIlroy had lost his opening match since 2013 when Match Play was single elimination.

“If I had played anyone else, I might have won,” McIlroy said. “Overall, I can’t be too disappointed. But at the same time, when standing on the 14th tee just having won three holes in a row, I thought I had him going into a tough stretch of the golf course. But he put up three birdies in a row, and you can’t do anything about that.”