Dan Evans came from a set down to beat world No 17 Karen Khachanov 4-6 6-3 6-4 and reach the quarter-finals of the Rotterdam Open.
After dropping the opening set, Evans raised his game and got an early break in the second set before levelling the match.
Evans moved 4-1 ahead in the deciding set as Khachanov smashed balls into the indoor roof in frustration. Even though the Russian cut the deficit he could not avoid defeat as Evans secured a quarter-final against either Gael Monfils or Giles Simon.
Monfils started his title defence with a convincing 6-3 6-2 victory over Portugal's Joao Sousa.
The 33-year-old Frenchman, who is looking to become the first player to win back-to-back Rotterdam titles since Sweden's Robin Soderling in 2011, next faces compatriot Simon who beat Mikhail Kukushkin 7-6(3) 3-6 6-3.
Top seed Daniil Medvedev crashed out as he lost 6-4 6-3 to world No 104 Vasek Pospisil.
World No 5 Medvedev, long-touted as one of the most likely of the new generation of players to win a Grand Slam, saw his challenge ended in just 68 minutes by Pospisil.
The 29-year-old Canadian, who continues a fine run of form having reached the final at the Open Sud de France in Montpellier last week, managed to save five of six break points while converting three of his own en route to a huge upset.
In an all-Spanish showdown, Pablo Carreno Busta beat sixth seed Roberto Bautista Agut 6-4 2-6 7-6(4) to qualify for the quarter-finals after a battle lasting nearly two-and-a-half hours.
Carreno Busta fired 11 aces and saved seven break points to advance at his higher-ranked compatriot's expense.
Belgian fourth seed David Goffin battled back from a set down and saved two break points in the decider to beat local hope Robin Haase 3-6 7-6(5) 6-4.
Goffin will face Italian Jannik Sinner, who was awarded a walkover after his opponent Radu Albot withdrew.