Roger Federer reveals moment when he doubted his progress against Philipp Kohlschreiber at Rotterdam Open

Roger Federer defeated Philipp Kohlschreiber in the second round of the 2018 Rotterdam Open on Thursday, 15 February, and the 20-time Grand Slam winner has revealed that he had doubts during the game after giving up any hope of winning the first set.

Every time the 36-year-old took the lead, the German successfully levelled the score. This went on till the scoreline reached 6-6, forcing a tiebreaker in the opening set.

Initially, Kohlschreiber was in the driver's seat to clinch the first set as he had a 5-2 lead in the tiebreak. The score eventually moved to 6-4 with Federer still trailing. But the Swiss ace was lucky enough to survive two set points before bouncing back to wrap up the set.

Federer then went on to take the second set as well, clinching the match 7-6, 7-5 to make it to the quarter-final of the Rotterdam Open.

"I was preparing for the second set, being down one set. I don't care how positive a person you are," Federer explained, as quoted by ATP's official website.

"You just see negativity flying all around you, I am down 4-6, I messed up, I should have done this, I should have done that. I'm at the mercy of my opponent.

"It's a bad feeling, but when you do come back and snatch the set, it's such a key moment in the match and I was able to utilise that.

"It was extremely complicated tonight. I couldn't find my range or my rhythm. I think Philipp did that to me, it was a struggle. Today, when the score was close, I couldn't release my shots. So it was a battle... It was quite the relief at the end."

Federer is now edging closer towards clinching the World No. 1 spot following his straight-set victory over Kohlschreiber. He will now face 30-year-old Robin Haase in the quarter-final of the 2018 Rotterdam Open and a victory over the Dutchman will see him take over from Rafael Nadal as the top-ranked player. If Federer takes top spot again, he will replace Andre Agassi as the world's oldest No. 1.