PHOTOS: Serena dominates in return; Murray knocked out

'It's going to come and I'm taking it one day at a time. I'm just fortunate to be back here on these courts playing tennis. Everything is truly amazing.'

Former world number one Serena Williams looked sharp in her return to the hardcourts after a week-long break, soundly defeating Daria Gavrilova 6-1, 6-2 on Monday to advance to the second round of the Cincinnati Masters.

Williams, who made the Wimbledon final last month but withdrew from last week's Rogers Cup in Montreal for personal reasons, cracked eight aces and was never broken as she dispatched the 24-year-old Australian.

"I realised after Wimbledon that this is a journey for me," the 36-year-old Williams said.

"It's going to come and I'm taking it one day at a time. I'm just fortunate to be back here on these courts playing tennis. Everything is truly amazing."

Next up for the 23-times Grand Slam champion is a second-round clash on Tuesday with two-time Wimbledon winner Petra Kvitova, who had a first round bye.

Aryna Sabalenka of Belarus came from behind to defeat Johanna Konta 4-6, 6-3, 6-4 in their first round tussle.

Konta had 10 double faults and was broken four times by the 20-year-old, who will face big-serving ninth seed Karolina Pliskova on Tuesday.

US Open finalist Madison Keys and former world number one Victoria Azarenka also advanced.

Keys, the 11th seed, fired 13 aces as she eliminated fellow American Bethanie Mattek-Sands 3-6, 6-7(3), 6-4.

Azarenka, working her way back up the world rankings from her current number 87 after the birth of a son, overcame Carla Suarez Navarrao of Spain 6-7(5), 6-2, 6-4.

Azarenka will meet sixth seed Caroline Garcia in the second round.

Pouille outlasts Murray in Cincinnati opener

Andy Murray's comeback following hip surgery hit another roadblock on Monday after he was beaten 6-1, 1-6, 6-4 by France's Lucas Pouille in the first round of the Cincinnati Open.

The Scot went under the knife in January but has had a frustrating time since he came back to the ATP circuit in June.

The former world number one had hoped to build on the momentum that had carried him into the quarter-finals of the Citi Open before he pulled out of the Washington tournament citing fatigue.

But it was world number 17 Pouille who proved to be the more resourceful as he claimed his first win in five tries against Murray.

Murray, whose ranking plummeted into the 800s last month but has now risen to 375, has fallen at the first hurdle in two of the four tournaments he has contested this year.

"I only lost four more points in the match than him," said Murray, who won 82 points to Pouille's 86.

"It was tight. He's a top 20 player. If I can improve by 10, 15 percent, you turn a lot of those matches around."

Pouille said he was pleased with how he fought against the former world number one.

"I'm very happy, especially with the way I fought until the end," he said.

"I tried to do my best in the third set and then until the end I played very aggressive and I'm very pleased with that."

American Sam Querrey overcame 38 aces by ninth seed John Isner to send his friend and compatriot packing with a 6-4, 6-7(5), 7-6(5) win.

The win was the first time Querrey has come out on top in a third set tiebreaker this year after losing seven in a row.

"I've lost a handful of tough matches this year but I feel like I’m starting to play better now, a little more consistent," the 30-year-old Californian said.

"Hopefully I can end the year on a strong note. Usually I feel like I play my better tennis at the beginning of the year so I'm going to try to flip it and play better at the end this year."

Wimbledon champion Novak Djokovic defeated American Steve Johnson 6-4, 7-6(4) in a hard-fought match under the lights.

The 31-year-old Serb is searching for his first Cincinnati Masters title after five finals.

Swiss Stan Wawrinka dug deep and ultimately prevailed 6-2, 4-6, 6-3 against twelfth seed Diego Schwartzman in their first career meeting to set up a highly-anticipated battle with Japan's Kei Nishikori.

Spain's Pablo Carreno Busta, Briton Kyle Edmund and Canadian young gun Denis Shapovalov also advanced to the second round.

The tournament lost its top seed when world number one Rafael Nadal withdrew after winning the Rogers Cup on Sunday.

World number two Roger Federer, who skipped the Toronto event, is now the highest seed.