Rory McIlroy pulled off a brilliant victory from the jaws of defeat when the World Golf Championships-Accenture Match Play Championship began in Tucson.
Four down to American Kevin Na early on and still two behind with only four holes remaining, the 20 year old fourth seed eagled the next and won on the final green as his opponent, ranked 61st in the world, felt the heat.
It was just the sort of thing that would have hugely impressed Ryder Cup Captain Colin Montgomerie, who earlier this week said: "I want to see guys who show guts and determination, guys who are maybe two or three down with four or five holes to play but who battle back to win."
The young Northern Irishman, hoping for a debut against the Americans in October, reached the quarter-finals last year.
“I got off to a very slow start,” said McIlroy. “Kevin got off to a very good start. Four down through six, it wasn't looking too good. I just hung in there and played some good golf around the turn.
“I think I hit a really good drive on 15, which after missing the putt on the previous hole to get back to one down. And then to go square through 16, I knew I was in a pretty good position and I think I hung in well and had a great drive on the last - which put him under a little bit of pressure.
“I was pretty fortunate to get through today. I'll need to play a lot better if I want to progress into the latter stages of the tournament.”
There was a superb fightback from Ian Poulter as well. He went from two up to two down against former Open Championship winner Justin Leonard, but won on the 19th.
Out, though, went three-time Major winner Padraig Harrington, who lost 3 and 1 to Indian Jeev Milkha Singh.
McIlroy is already the only Irishman left in the event as it moves down to the last 32, Graeme McDowell having gone down 2 and 1 to in-form Luke Donald.
Paul Casey, last year's runner-up to Australian Geoff Ogilvy, had a resounding 5 and 4 success over Canadian Stephen Ames, but that was far from the biggest victory of the day.
Ames' fellow countryman Mike Weir defeated big-hitting Spaniard Alvaro Quiros 8 and 6 - he birdied nine of the first ten holes - while Ogilvy began his defence with a 7 and 5 win over Alex Noren.
It was not a good day for the Swedes. As well as Noren, Peter Hanson lost to Australian Robert Allenby and former winner Henrik Stenson withdrew after one hole against American Ben Crane because of flu-like symptoms.
Ross Fisher fell at the first hurdle in his bid to do a Match Play double after his success in Spain last October. He was defeated 5 and 4 by Thai Thongchai Jaidee.
Open Championship winner Stewart Cink matched McIlroy's fightback when he also recovered a four hole deficit to beat Italian Edoardo Molinari on the last - and Molinari's brother Francesco lost on the 21st to Zach Johnson.
Sergio Garcia went through against David Toms and Dane Anders Hansen had a notable 2 and 1 win over US Open Championship winner Lucas Glover.