Defending champion Roger Federer cruised into the quarter-finals of the Western & Southern Open with a 6-1 6-1 demolition of South African Kevin Anderson.

Swiss second-seed Federer needed just 55 minutes to register his easy win but top seed Novak Djokovic, third seed Andy Murray and fifth seed Stan Wawrinka were all taken the distance in their matches at the US Open warm-up event in Cincinnati.

Playing in his first tournament since losing the Wimbledon final to Djokovic last month, Federer looks fresh and rested and advanced to a last eight encounter against Spain's Feliciano Lopez, who upset 2013 Cincinnati champion Nadal 5-7 6-4 7-6(3).

Djokovic looked in danger when he dropped the opening three games of the final set against 13th-seeded Belgian David Goffin, but roared back for a 6-2 2-6 6-3 win to set up a French Open final rematch against Stan Wawrinka.

The Swiss claimed his second grand slam title with a four-set victory over Djokovic in Paris and beat Croatia's Ivo Karlovic 6-7(2) 7-6(5) 7-6(5) to book a showdown against the top seed.

Djokovic and Wawrinka will meet for the 22nd time on Friday, but it will be their first clash since the Swiss triumphed at Roland Garros in June.

Murray, who won the Rogers Cup in Montreal on Sunday, looked a little jaded after a tough two weeks but the Briton somehow recovered to beat Grigor Dimitrov 4-6 7-6(3) 7-5 in a little under three hours after twice looking to be headed for defeat.

Results:

2-Roger Federer (Switzerland) beat 15-Kevin Anderson (South Africa) 6-1 6-1
3-Andy Murray (Britain) beat 16-Grigor Dimitrov (Bulgaria) 4-6 7-6(3) 7-5
Feliciano Lopez (Spain) beat 8-Rafa Nadal (Spain) 5-7 6-4 7-6(3)
1-Novak Djokovic (Serbia) beat 13-David Goffin (Belgium) 6-4 2-6 6-3
6-Tomas Berdych (Czech Republic) beat Tommy Robredo (Spain) 6-0 6-1
5-Stanislas Wawrinka (Switzerland) beat Ivo Karlovic (Croatia) 6-7(2) 7-6(5) 7-6(5)
Alexandr Dolgopolov (Ukraine) beat Jerzy Janowicz (Poland) 6-3 3-6 6-4
12-Richard Gasquet (France) beat 7-Marin Cilic (Croatia) 7-5 6-3

Williams will take on Ivanovic for a place in the semi-finals [AP]

In the women's draw, defending champion Serena Williams cruised into the quarter-finals with a 6-0 6-2 win over Italy's Karin Knapp on Thursday while Swiss teenager Belinda Bencic's remarkable run came to an end.

Williams, who was upset by Bencic last week in the semi-finals of the Rogers Cup in Toronto, needed 54 minutes to get by Knapp and set up a showdown with Serbian Ana Ivanovic in what will be a rematch of last year's final.

Sixth seed Ivanovic advanced after beating American Sloane 2-6 6-4 6-1. The Serb has beaten Williams only once in nine meetings with the only win coming at in a last-16 clash at the 2014 Australian Open.

Rogers Cup champion Bencic took an eight-match winning streak into her last-16 clash with Lucie Safarova but the 18-year-old Swiss was forced to retire with a muscle strain after her seventh-seed opponents took the first set 6-2.

"First of all, I don't think it's very serious," Bencic told reporters. "I just wasn't 100 percent today, and to beat Lucie or even compete against her, you need to be 100 percent."

Results:

3-Simona Halep (Romania) beat 15-Andrea Petkovic (Germany) 4-6 6-4 6-2
14-Elina Svitolina (Ukraine) beat Caroline Garcia (France) 6-0 6-3
6-Ana Ivanovic (Serbia) beat Sloane Stephens (U.S.) 2-6 6-4 6-1
1-Serena Williams (U.S.) beat Karin Knapp (Italy) 6-0 6-2
Jelena Jankovic (Serbia) beat 8-Karolina Pliskova (Czech Republic) 6-2 3-6 7-5
Anna Karolina Schmiedlova (Slovakia) beat Varvara Lepchenko (U.S.) 6-3 3-6 6-4
7-Lucie Safarova (Czech Republic) beat Belinda Bencic (Switzerland) 6-2 0-0 (Bencic retired)
Anastasia Pavlyuchenkova (Russia) beat Victoria Azarenka (Belarus) 1-6 3-0 (Azarenka retired)

Source: Reuters