Monte Carlo - Grigor Dimitrov benefited from a second-set collapse by David Goffin on Friday to reach the Monte Carlo Masters semi-finals for the first time with a 6-4, 7-6 (7/5) victory.
The 26-year-old Bulgarian got the better of a nervy Goffin in a repeat of last year's ATP Tour Finals final to book a last-four clash with either defending champion Rafael Nadal or Austrian Dominic Thiem.
"I felt like I could have done things a bit better, especially at the beginning of the second set," said Dimitrov.
"Hopefully in my next match I can do better in those moments."
The pair will team up later on Friday in the doubles quarter-finals, but there was little charity on offer from Dimitrov towards his partner turned opponent.
Dimitrov has struggled on clay in the past and has never passed the French Open third round, but he was too strong for sixth seed Goffin in the Monaco sunshine.
Fourth seed Dimitrov edged a tight opening set after failing to serve for it as Goffin produced a poor service game at 5-4 down, before the Belgian recovered to race into a 5-1 lead in the second.
But Goffin wasted three set points on his own serve as he tightened up on the most important points, and Dimitrov broke twice to force a tie-break.
The world number five wrapped up victory in the breaker on his second match point to claim one of the best wins of his career on clay.