American Jimmy Walker survived a marathon final day and held off the determined challenge of defending champion Jason Day to win his first major title in the weather-affected US PGA Championship.
Walker carded a closing 67 at Baltusrol to finish 14 under par, one shot ahead of Day after the world number one stunningly eagled the final hole to pile on the pressure.
A par was still good enough for Walker to become the eighth wire-to-wire winner of the US PGA - and the first since Phil Mickelson at the same venue in 2005 - and the 37-year-old held his nerve after pitching to 30 feet from right of the green.
Walker's win booked a second consecutive appearance in the Ryder Cup and completed a clean sweep of 2016 majors by first-time winners after Danny Willett (Masters), Dustin Johnson and Henrik Stenson (Open Championship).
Stenson was in contention for back-to-back majors until a double bogey on the 15th ended his chances, the 40-year-old Swede having to settle for a tie for seventh with playing partner Martin Kaymer, who eagled the last in a closing 66.
One of 10 players forced to play 36 holes on Sunday after the previous day's thunderstorms, Walker started his third round at 7.40am local time and carded a 68 to take a one-shot lead into the final round.
A run of nine straight pars was enough to keep Walker's nose in front before the world number 48 - the lowest ranked major winner since world number 108 Keegan Bradley won the 2011 US PGA - doubled his lead in brilliant fashion by holing out from a bunker on the 10th.
Day, who was looking to become the only player after Tiger Woods to win back-to-back titles since the US PGA became a strokeplay event in 1958, had bogeyed the first and third but bounced back with birdies on the fifth and ninth.
The 28-year-old also immediately answered Walker's bunker shot by making a birdie on the 11th, only for Walker to hole from 30 feet on the same hole 10 minutes later.
Day was unable to pick up any further shots before hitting a superb approach to within 15 feet of the hole on the 18th, prompting a roar from the crowd which forced Walker to back off his birdie putt on 17 before crucially holing from eight feet for a three-shot lead.
Walker, who led after an opening 65 and shared the halfway lead with compatriot Robert Streb, said at the presentation ceremony: "I was thinking if I could birdie 17 that would put it out.
"Then we made birdie but sometimes things just don't come easy. Jason is a true champion...eagle on 18, that's unreal. That really put it on me to make a par - and pars are hard sometimes.
"There's a lot of emotion going on out there. It's tough. I felt a ton of support from the crowd and it was amazing. It was a battle all day."
Day, who was among the first to congratulate Walker on the 18th green, said: "I tried to give it a good run. I felt like I played pretty decent the whole week and unfortunately it just was not good enough. But I can't be disappointed. Jimmy played great all week and is a deserving winner."
American Daniel Summerhays finished three shots behind Day in third, with Branden Grace, Hideki Matsuyama and Brooks Koepka another stroke behind.
Stenson, Kaymer and Streb shared seventh on eight under, with Stenson left to rue the double bogey on the 15th which ended his chances of a second major title in the space of 15 days.
The 40-year-old Swede said: "It was a long day and I never felt like I brought my A game.
"I was struggling most of the day. I think I hit more poor shots in the two rounds today than in the previous six or seven rounds combined.
"Despite that, I thought I was hanging good. I was trying to push, which I had to. I was two or three behind coming into the last five or six holes. Then on 15, I'm trying to get to the back pin with a three-quarter nine (iron) and winged it over the loft and ended up with a double and that was the end of it for me.
"All in all, I'm pretty pleased to come off the win at The Open and then be right up there contending the week after."
England's Tyrrell Hatton, who finished fifth behind Stenson at Royal Troon a fortnight ago, carded a closing 68 to finish in a tie for 10th alongside compatriot Paul Casey, who shot 67.
Hatton, who also finished second in the Scottish Open this month, said: ''It's been three really good weeks and it's really good for my confidence.
''I'm just really happy to finish birdie, birdie in both rounds today and post a decent score. It's a great end to a great week.
"I found it difficult to get close to the pins because the greens were so soft and I struggled a little bit with my game today, but I ground out a good score with a good finish."