Sergio Garcia bowed out of the WGC-Accenture Match Play Championship after an extraordinary act of sportsmanship, but Graeme McDowell pulled off yet another great escape at Dove Mountain.
McDowell beat Hunter Mahan on the 21st hole after recovering from two down with two to play, inflicting more misery on the man he beat in the decisive final Ryder Cup singles match at Celtic Manor in 2010.
But even that performance was overshadowed by a remarkable incident in the match between Garcia and Rickie Fowler, who ultimately birdied the 18th to seal a hard-fought victory.
Garcia had needed a drop away from a colony of bees on the edge of the sixth green, where he was heard saying to the rules official: "I don't want to hit the shot, I've had bad experiences with bees."
And clearly feeling that he had taken too long to play his second shot, Garcia then offered Fowler a half on the next hole, despite the Spaniard facing five feet for par and Fowler more than three times that distance.
Garcia did win the eighth to move three up, but Fowler went on to birdie the ninth, 10th, 16th and 18th to book a quarter-final clash with Jim Furyk, who saw off Harris English on the 18th.
"I don't regret it at all, he played much better than me on the last 10 holes and he deserves the win," Garcia told Sky Sports. "This is a gentleman's game and lately it hasn't felt like it's been like that.
"This is the way I was brought up by my dad; I felt like my drop on six took too much time. If I had been in his position I would not have enjoyed waiting so long to hit my birdie putt after the great shot he hit.
"I thought it was the only thing I could do on seven to make myself feel better and not feel guilty about anything. I was playing as hard as I could and got three up but he started making birdies and I wasn't able to keep up."
Fowler admitted he was not initially sure what Garcia was proposing, adding: "I had to find out what he was asking or offering there, it took me a few (seconds) to kind of realise. It would be stupid not to take a half.
"He said, 'You wanna halve?' I didn't know what he meant. I thought maybe he had a sandwich."
McDowell had reached the third round thanks to two superb fightbacks, recovering from three down with three to play to beat Gary Woodland on the 19th and rallying from two down with four to play against Hideki Matsuyama before winning on the 18th.
And after beating 2012 winner Mahan with a birdie on the third extra hole, it means the only time the former US Open champion has led a match all week has been on the final hole.
"It's entertaining for sure but I'd much rather have it much easier, believe me," said McDowell, who had three-putted the 16th to fall two down.
"I can't get my head around it. I was pretty sure I was beat against Gary Woodland, yesterday I thought I had a chance and today walking off the 16th green I thought I was beat again.
"The par save on the second play-off hole was just ridiculous [he holed from 20 feet there]. I can't believe it really, I have just robbed three players at this tournament and I can't believe I am still in it."
McDowell will face Victor Dubuisson in the quarter-finals, the Frenchman holding off a late rally from Bubba Watson to win on the 18th and edge ever closer to securing his Ryder Cup place.
"I'm definitely ready because I have good experience of match play as an amateur," he said. "I hope the three matches I have won will help me get into the team."
European captain Paul McGinley added on Sky Sports: "It's great experience for him and I like that he was pushed to the 18th and played it like a real professional. It means a lot and is further evidence that he is ready to step up to the next level."
South Africa's Louis Oosthuizen had been the first man into the last eight after thrashing Webb Simpson 5&4, the former Open champion being six under for 14 holes to set up a clash with Australian Jason Day, who beat George Coetzee 3&1.
The remaining quarter-final sees Ernie Els take on Jordan Spieth after Els birdied the 18th to beat Jason Dufner and Spieth knocked out defending champion Matt Kuchar 2&1.