Top seeds Djokovic, Federer reach semi-finals

World number one Novak Djokovic brushed aside Switzerland's Stan Wawrinka in straight sets to advance to the semi-finals of the ATP and WTA Cincinnati Masters Friday.

The top-seeded Serb breezed past Wawrinka with little difficulty in just over an hour, winning 6-4, 6-1 to avenge his defeat to the Swiss in the French Open final.

Djokovic will face Ukrainian qualifier Alexandr Dolgopolov, who upset Czech sixth seed Tomas Berdych 6-4, 6-2. The Serb owns a 4-0 record in that series, most recently winning in Miami five months ago.

Before this week, Dolgopolov had lost all four of his previous matches at the pre-US Open event.

Six-time winner Roger Federer crushed Spain's Feliciano Lopez 6-3, 6-4, earning a 12th straight win without a loss in that series.

The second seed lost just four points on serve in the opening set as he steamrolls through his matches in what will be his lone tune-up for the Open which begins a week from Monday.

The defending champion Federer, who is chasing a fifth trophy this season, improved to 43-7 on the season after a minimal 61-minute sweep.

"I'm very happy with how I got out of the blocks again," said Federer, who last played in the Wimbledon final. "I wasn't sure how I'd come back from vacation and training. I'm pleased with how I'm playing.

"I'm playing great tennis and I'm feeling good, feeling healthy and enjoying myself. That's important at this point of my career.

"I feel better at the net than I ever have and I hope to keep that up. I want to win the US Open again but I still have work to get done here."

- Murray rallies -

Britain's third seed Andy Murray rallied after losing the first set to Richard Gasquet, turning the tide for a 4-6, 6-1, 6-4 win.

Murray, who is trying to back up last week's Montreal title with his third in Cincinnati, fired 35 winners and broke four times in just over two hours against his French opponent.

The Scot admitted that his stamina is running low.

"I'm obviously tired, I've played a lot of matches, a lot of late nights. My recovery hasn't been perfect either.

"I'm just happy I managed to fight through a lot of tough matches, difficult situations, and hopefully that will stand me in good stead for the US Open."

World number one Djokovic improved to 18-4 over Wawrinka.

"It was the best performance I had so far this week. It came at the right time against one of my biggest rivals and the guy I lost to last time we played in the finals of French Open," said Djokovic.

"Obviously I approached this match very seriously in trying to prepare myself and get myself in a good position to win. That's what I have done."

Djokovic is on a mission to finally win Cincinnati and become the first player in history to complete a matched set of all nine Masters 1000 trophies.

He has lost four finals here, two apiece to Murray and Federer.

Defending champion Serena Williams swept the last six games to overhaul Ana Ivanovic 3-6, 6-4, 6-2 in a repeat of the 2014 final won by the American. Her next opponent will be Ukrainian 14th seed Elina Svitolina, who upset Roland Garros finalist Lucie Safarova 6-4, 2-6, 6-0.

Williams said that after playing on the back foot in the first set, she raised her game to post her ninth victory in 10 meetings over the former Roland Garros champion from Serbia.

"I was lethargic in the first set and she played incredibly well. I just had to do better.

This was my best performance since (winning) Wimbledon. I hope to take the momentum into the next match."

Third seed Simona Halep beat Anna Schmiedlova 7-6 (7/3), 6-2 while former champion Jelena Jankovic defeated Anastasia Pavlyuchenkova 6-4, 6-2 to complete the women's semi-final line.

Halep can overtake Maria Sharapova on second in the rankings if she reaches the final.

(AFP)