Roger Federer moved to within one victory of returning to world number one after a 7-6 (10-8) 7-5 win over Philipp Kohlschreiber at the Rotterdam Open.
The Swiss, who last sat atop the ATP rankings in November 2012, needs to reach the semi-finals to usurp Rafael Nadal, and he advanced into the last eight on Thursday.
At the end of a hard-fought battle, Federer extended his perfect record over Kohlschreiber to 13-0, the 36-year-old chasing a third title at this ATP 500 event following successes in 2005 and 2012.
Both men squandered set points in the first but it was Federer who converted when it mattered most to get his nose in front.
Kohlschreiber stuck with the 20-time grand slam champion in the second but he could not escape the irresistible Federer force.
The opening dozen games were dominated by the serve, the only scare arriving at the business end for Kohlschreiber with Federer successfully challenging at 6-5 and 30-30 to earn a set point.
It passed him by as he sent a forehand wide and it was the German's turn to take the advantage with a fierce backhand return for a 3-2 lead in the breaker.
That became 6-4 but Kohlschreiber went wide under pressure as Federer stayed alive, wasting two set points of his own before finally capitalising on the third with a trademark forehand.
Kohlschreiber refused to go away, however, rescuing three break points at 1-1 in the second but he shot himself in the foot as a double-fault at 5-5 handed Federer the chance to serve for the match, sealed with a deft volley that proved just out of reach of his opponent.