Walden has been in superb form in China
Qualifier Ricky Walden stunned world champion Ronnie O'Sullivan 10-8 to win the Shanghai Masters in China.
World number one O'Sullivan looked on course for his 22nd ranking title and a record-equalling third title in a row.
But his fellow Englishman fought back, winning five of the last seven frames and clinching his first ranking title at the age of 25 with a break of 105.
"I'm now going to go to Las Vegas with my friends and really enjoy it," said Chester-born world number 35 Walden.
"I am thrilled to bits to win my first tournament. I had a bit of luck, especially when I missed a few easy chances, but I managed to stay calm and I hope I can go on and achieve more now."
Walden's impressive win moved him up to 17th in the latest rankings and on the verge of a coveted top-16 place.
I never put him under any pressure so I deserved to lose
"I certainly want to get into that top 16 and win more tournaments," said Flintshire-based Walden, who beat Stephen Hendry, Neil Robertson, Steve Davis and Mark Selby on his way to the final.
The defeat also ended O'Sullivan's hopes of becoming the first professional player for 15 years to win three consecutive ranking titles.
"Ricky played very well. He's a good player and it's good that he has won an event," he said.
"I never put him under any pressure so I deserved to lose. I have still had a good week to get to the final."
Only Scotland's Stephen Hendry, Welshman Ray Reardon and fellow Englishman Steve Davis have ever won three rankings events in a row.
Ronnie O'Sullivan (Eng) 8-10 Ricky Walden (Eng)
88-0 47-61 20-113 (74) 4-99 (99) 86-22 (58) 95-0 (64) 87-1 (87) 38-77 78-0 (78) 0-104 (95) 122-5 (108) 21-78 25-65 82-16 (82) 23-73 (59) 4-88 (52) 66-30 11-105 (105)