Big-hitting Ivo Karlovic scored a big upset win over home favourite and second seed Stan Wawrinka in the first round of the Swiss Indoors Basel on Wednesday.
The Croat looked almost dead and buried after finding himself a set and 1-3 down, but sneaked a break in the second set to get back on level terms before bossing the tie-break and levelling the scores.
Firing 21 aces and winning 89% of his first service points, Karlovic gradually wore his opponent down, breaking early in the third set before eventually closing out the 3-6 7-6 (7-2) 6-4 victory with three consecutive aces.
Elsewhere, fourth seed Kevin Anderson and seventh seed Marin Cilic both advanced to the second round with straight sets victories.
Anderson's serve was on point as he dispatched Borna Coric 6-3 6-2, while Cilic fired 14 aces but had to work a little harder for his 6-3 7-6 (7-3) victory over wild card Marco Chiudinelli.
There were also first-round wins for Jack Sock and Teymuraz Gabashvili.
David Goffin and Andy Mannarino faced each other in a second-round encounter later in the day, with Goffin emerging a 6-4 6-3 winner.
Grigor Dimitrov was up against third seed Rafael Nadal in the final match, with the Spaniard battling to a 6-4 4-6 6-3 victory to become the second man after Goffin to reach the quarter-finals.
The Spaniard found himself an early break down in the deciding set but recovered in some style to win six of the last seven games.