Reigning champion Judd Trump crashed out of the World Grand Prix following a 4-3 defeat by Tom Ford at the Coventry Building Society Arena on Wednesday.
Trump was seeking a fourth title at the elite 32-man event, having lifted the trophy in 2015, 2019 and 2020.
However, his quest came to a shuddering halt as Ford, who beat John Higgins 4-2 in the opening round, prevailed on the final black.
The Ace had won 12 of the 17 previous meetings between the players and controlled the opening two frames, but his opponent hit back with breaks of 133 and 65 to level.
The next two frames were shared as neither player was able to build fluency with the contest going down to the wire.
Both had chances in the decider, but it was Ford who converted his to scrape over the line.
The former Paul Hunter Classic finalist sets up an all-Leicester clash with World champion Mark Selby, who beat Mark Allen 4-2.
The Jester had lost each of his three previous meetings with the Pistol in events televised on ITV, but stopped the rot with breaks of 85 and 78 along the way.
Ronnie O’Sullivan began his quest for a second title with a 4-1 win over UK Championship quarter-finalist Andy Hicks and will play Hossein Vafaei, who had a top run of 119 as he defeated Gary Wilson by the same scoreline.
Meanwhile, Neil Robertson hit breaks of 108 and 74 in his 4-1 victory over Anthony Hamilton.
Next up for the 2020 champion is Yan Bingtao, who enjoyed a 4-0 success against Martin Gould.
Scottish Open winner Luca Brecel maintained his impressive form – runs of 105, 100 and 88 sealing a 4-1 win over Welsh Open champion Jordan Brown – while Jimmy Robertson overcame Matthew Selt 4-2.
World Grand Prix Snooker 2021 Results
Wednesday December 15
Ronnie O’Sullivan 4-1 Andy Hicks
Gary Wilson 1-4 Hossein Vafaei
Jimmy Robertson 4-2 Matthew Selt
Luca Brecel 4-1 Jordan Brown
Yan Bingtao 4-0 Martin Gould
Judd Trump 3-4 Tom Ford
Neil Robertson 4-1 Anthony Hamilton
Mark Selby 4-2 Mark Allen