Roger Federer engineered a 6-1, 6-1 rout in less than an hour, outclassing the big-serving Kevin Anderson to join Novak Djokovic in the quarter-finals of the ATP and WTA Cincinnati Masters on Thursday.

Switzerland's Federer swept the first set in 21 minutes and began the second set with a break of South African Anderson.

While the second seed was able to make it all look easy, it was a slog for an exhausted Andy Murray as the third-seeded Montreal title-winner needed a shade under three hours to put down Grigor Dimitrov 4-6, 7-6 (7/4), 7-5.

Dimitrov led a set and two breaks before Murray hauled the second set back. The Bulgarian then owned the third 5-2 but could not close it out despite getting to match point.

Murray gathered the last of his reserves to take the win, his 26th at the tournament which he won in 2008 and 2011.

Djokovic also survived a scare in the pursuit of a first career Cincinnati title, with the top seed holding off David Goffin 6-4, 2-6, 6-3.

Djokovic, aiming to become the first man to win all eight Masters 1000 events, nearly found himself on the sidelines as his 13th-seeded Belgian opponent won the second set and went two breaks up in the decider.

But the experienced Serb pulled back from the brink, levelling at 3-3 and ran out the winner after a tense one and three-quarter hours.

Djokovic stayed alive despite seven double-faults and five breaks of his serve.

Djokovic will face Stan Wawrinka in the next round after the Swiss fifth seed prevailed over Ivo Karlovic to win 6-7 (2/7), 7-6 (7/5), 7-6 (7/5).

Sixth seed Tomas Berdych crushed Spain's Tommy Robredo 6-0, 6-1.

Frenchman Richard Gasquet knocked out US open winner Marin Cilic, the seventh seed, on the cusp of a Grand Slam title defense, leaving the Croatian hurting after a 7-5, 6-3 loss.

Former champion Rafael Nadal, seeded eighth, lost to Spanish compatriot Feliciano Lopez 5-7, 6-4, 7-6 (7/3) in another night-time marathon.

Women's holder Serena Williams dispatched Karin Knapp 6-0, 6-2, while sixth seed Ana Ivanovic overhauled Sloane Stephens 2-6, 6-4, 6-1.

Williams won't get her wish in the next round as she plays former world No. 1 Ivanovic who is having a strong season. It will be a re-run of their final from 12 months ago.

French Open finalist Lucie Safarova advanced to the quarter-finals when injured opponent Belinda Bencic quit trailing 6-2. Jelena Jankovic punished eighth seed Karolina Pliskova 6-2, 3-6, 7-5.

Two-time Australian Open champion Victoria Azarenka had to stop with leg pain after being taped at the end of the first set, handing a 1-6, 3-0 win to Russian Anastasia Pavlyuchenkova.