British qualifier Dan Evans produced the performance of his career to stun 11th seed Kei Nishikori on the opening day at the US Open.
The 23-year-old from Birmingham, ranked 179th, outplayed the Japanese star in a 6-4 6-4 6-2 victory at Flushing Meadows.
Evans, playing in his first Grand Slam main draw away from Wimbledon, will face Australian Bernard Tomic next.
And he will be optimistic of further progress as a superb run of form on North American hard courts rolls on.
The Briton, who by his own admission has had a poor attitude in the past, began converting his undoubted talent into results earlier this year, but victory over Nishikori is a major breakthrough.
"It's definitely a good one," said Evans. "That was pretty good out there to play so well and against someone so highly ranked.
"I felt pretty confident all through the week, and that was a good match. I wasn't worried."
Evans had too much variety for the Japanese player, with his sliced backhand and ability at the net helping him to what was in the end a relatively straightforward win.
After dropping serve early on, Evans fought his way back to level at 4-4 and broke once again with some fine volleying to grab the first set.
Evans had gone into the match with 14 wins behind him since heading to North America, and the winning habit served him well as the prospect of a huge upset loomed large in the second set.
After swapping breaks at the start, Evans appeared nerveless when he held to love at 4-4, and then broke for the set thanks to a vicious backhand slice that caught out Nishikori at the net.
Nishikori, 23, threatened a comeback at the start of the third but Evans saw off three break points and then broke to love - a lead he would not relinquish.
With Court 13 now bursting at the seams as passers-by edged into the alleyways to get a look at the first big upset of the tournament, Evans broke for the sixth time to seal victory after one hour and 57 minutes.
"I have played so many matches it's sort of like every day is rolled into one at the minute," added Evans.
"I didn't really know it was Monday today, either. It's just been going on. So it's been a good trip, and a few more days left yet."
Evans has looked remarkably unruffled throughout his four wins in New York, and said: "I knew I was a good player, but I just hadn't put it all together.
"I was pretty calm today. It wasn't like that much of a big deal what was happening on the court. I wasn't nervous serving it out.
"I just played another good match. I've played some good matches for the last five weeks.
"I really want to go far in the tournament, win a few more matches like today, and I'm ready to play again."
It was the second win of the day for British players after 30th seed Laura Robson earlier beat Lourdes Dominguez Lino 7-5 6-0 on the nearby Court 13.