CINCINNATI, United States (AFP) — Roger Federer began his US Open preparation with a quick 6-4, 6-4 defeat of Peter Gojowczyk in his first ATP Cincinnati Masters appearance since 2015.

The 20-time Grand Slam champion, who turned 37 last week, is pacing his tennis year, playing a limited schedule and skipping events when he feels the need to rest.

He has missed the last two editions of this tournament because of injury.

Eighth-seeded Petra Kvitova used her precision serve to overpower Serena Williams 6-3, 2-6, 6-3 in their second round match on Tuesday night.

Federer’s defeat of the 47th-ranked German in 72 minutes marked his first step towards a possible eighth title at the tournament.

“I felt good in that first match, to be honest, walking out, hardly any nerves. I think I knew what I had to do,” Federer said.

“The goal is now to recover from this match, take the positives with me. Of course the big goal is the US Open.”

The contest was the first for the Swiss since losing to Kevin Anderson in five sets in the Wimbledon quarter-finals on July 11.

Eighth seed Dominic Thiem was forced to withdraw without hitting a ball. He was suffering from a virus.

In the women’s draw, the second set of the Kvitova-Williams contest was significant for Williams because it was her first set win this season against a top 10 opponent.

The 23-time Grand Slam champion won her first-round match over Daria Gavrilova in straight sets, 6-1, 6-2, on Monday, but appeared to run out of gas in the third set against Kvitova.

Just two weeks ago, Williams suffered the worst defeat of her career in San Jose when she was crushed 6-1, 6-0 in 51 minutes by world number 39 Johanna Konta.