Unseeded Grigor Dimitrov came from a set down to beat Marcos Baghdatis 6-7 (4/7), 7-6 (7/0), 6-3 on Friday to reach the semi-finals of the Rotterdam World Tennis tournament.
The Bulgarian's performance showed that he is returning to the kind of form he produced at the start of the year, when he reached the final in Brisbane before losing to Andy Murray.
Dimitrov had also beaten Baghdatis in three sets in that tournament, and here he repeated the feat to set up a last-four showdown against either second seed Juan Martin del Potro or Finn Jarkko Nieminen.
He lost the opening set 7-6, but levelled the match by winning the second 7-0 in another tiebreak.
In the decider, Baghdatis fought to recover from 4-2 down and saved a match point in the eighth game to hold serve.
But the 41st-ranked Dimitrov clinched victory a game later on his second opportunity, as his opponent's return sailed long to end a contest that stretched over two and a half hours.
He advanced despite converting just two of 13 break-point chances over the course of the match.
Top seed Roger Federer, who is bidding to win the Rotterdam title for the third time, was due to play his quarter-final against Frenchman Julien Benneteau later.
The winner of that match will face either Martin Klizan of Slovakia or French fifth seed Gilles Simon in the last four.