Rory McIlroy and Min Woo Lee got off to winning starts at the WGC-Dell Technologies Match Play at Austin Country Club.
McIlroy saw off Scott Stallings 3&1 while Lee won a thriller against Sahith Theegala on the final hole.
Matt Fitzpatrick was out in the first match but the U.S. Open Champion suffered a shock defeat at the hands of JJ Spaun while Tyrrell Hatton also lost.
A par was good enough for McIlroy to win his opening hole after Stallings went too far right with his tee shot and the Northern Irishman won the fifth and sixth with birdies to give himself a cushion.
But missing the fairway left with his tee shot at the eighth and doing the same at the ninth let Stallings in, the American went par-birdie to win both holes and McIlroy was just 1UP turning for home.
That advantage was doubled when McIlroy's tee shot at the 202-yard 11th landed three feet from the hole. He knocked in the birdie and was in control from there, securing his point by knocking his tee shot in close at the short 17th.
McIlroy was glad to get off the mark with a new putter and driver in the bag.
He said: "Yeah, really good. That's the main thing this week. Obviously there's a ton of golf left this season, but to get a little bit of match play in our lives is good and get under pressure.
"There's a couple of putts on the back nine there that I was actually glad I had the hole. It's good practice, but at the same time I want to win the match.
"It was good. It was a good first starting for both those clubs, and they both performed pretty well."
On his round McIlroy added: "It was solid. You know, I think I birdied most of the holes that you should birdie out there. I didn't make many mistakes apart from a short little missed putt on the eighth hole.
"Overall, six birdies, one bogey. It was a pretty decent day and some tricky wind. The course was obviously soft after the rain the last couple days. Happy to get the win and move on to tomorrow."
The other match in Group 3 saw Denny McCarthy tie with Keegan Bradley.
Lee, playing in Group 11 alongside Fitzpatrick and Spaun, won his opening hole against Theegala but after losing the third and fourth he produced fireworks to get back in front. He nailed a huge putt for eagle at the short, par-four fifth and then posted another two at the par-three seventh, holing from the greenside bunker.
They traded blows from there and there was never more than one hole in it. Theegala got his nose in front with a birdie at 16, the first time he had been ahead since the fourth. He then fired his tee shot close at the 17th but Lee, after landing a few feet outside him, cranked up the pressure by sinking for birdie and they went down the last tied after Theegala missed.
Lee was the only one who could get up and down from short of the 18th green and that was enough to win 1UP.
"It was a highlight reel all day," said Lee. "Had two chip-ins, two eagles. Yeah, did a lot. Finished really well, I could have birdied all the last four, and yeah, it kind of sucked to lip out on 15 real hard.
"He had, not momentum, but I hit a bad drive after that, and it seemed like it went to his side, and I'm glad I holed a putt on 17 because if I missed that, he probably would have holed it and I would have lost.
"It was back and forth all day, and it was such a good match."
Fitzpatrick got off to a slow start, losing three in a row from the fifth and despite reducing the deficit to one as they approached the turn, Spaun won it with an impressive run from the 11th. He birdied the par three, posted another at the 12th then holed out for eagle from 107 yards at the par-four 13th.
That put him 4UP and it was over when Fitzpatrick missed a long birdie attempt at 15 and Spaun holed his from seven feet for a 5&3.
Hatton has work to do to escape Group 14 after losing 3&1 to Ben Griffin while Lucas Herbert is well placed after beating Russell Henley 1UP.
In Group 6, Xander Schauffele beat Cam Davis and Aaron Wise got the better of Tom Hoge.
