20-time Grand Slam champion Roger Federer held his nerves to edge Germany’s Philipp Kohlschreiber 7-6 (10-8) 7-5 to reach the quarter-finals of the Rotterdam Open and also move within one win of reclaiming the number one ranking.
Federer struggled through a 54-minute first set against Kohlschreiber to maintain his hopes, as he prevailed after a lengthy tie-break.
The second set was no less attritional, with Federer breaking for the only time in the contest to go 6-5 ahead before serving out to clinch a quarter-final place on his second match point.
“Tonight was complicated, I had to fight and struggle,” Federer said. “I had a good game plan going in, but I was never able to completely pull it off.”
Should Federer, 36, beat Robin Haase in their quarter-final tie on Friday, he will replace Rafael Nadal at the summit.
“I’ve struggled to try and get there. I had to win a lot of matches,” the Swiss said.
In the other match, second seed Grigor Dimitrov outlasted Serbia’s Filip Krajinovic 7-6 (7/4), 7-5 to also reach the quarter-finals.
Dimitrov has now reached a second straight quarter-final in the Dutch city, advancing with 13 aces and saving all four break points he faced.
The Bulgarian will face Andrey Rublev on Friday after the 20-year-old Russian struggled for nearly two hours before finally seeing off Damir Dzumhur 6-4, 7-6 (7/4)