Cincinnati - Roger Federer shook off the rust in his first match since Wimbledon as women's drawcards Maria Sharapova and Venus Williams withdrew injured from the ATP and WTA Cincinnati Masters on Tuesday.
Federer, who took more than a month off after losing the Wimbledon final to Novak Djokovic, beat Roberto Bautista Agut 6-4, 6-4, improving to 4-0 over the Spaniard without the loss of a set.
But the 34-year-old said that he needed time to adjust again to match conditions after his hiatus.
"It was a good win for me, it can only get tougher from here," said Federer, seeking a record seventh title here.
"I haven't played in a long time and I felt a bit rusty at times in the first set. I need matches right now, so it was good to start well here.
"I'm happy I got through this first one. Now I know what it's about.
"I have a day off tomorrow where I can think about how things went today, where I need to improve."
Sharapova has not played since Wimbledon and has now missed both of the major tune-ups prior to the US Open which begins in less than a fortnight.
The WTA number two is nursing a leg injury which also prevented her from playing last week in Toronto.
"It's a tough decision to make, but I think a wise one, in order to give myself the right amount of time to be as healthy as I can be for the Open, which I believe is very realistic," Sharapova said. "But I don't know if it would be realistic if I did compete and start tomorrow."
The Russian was joined as a victim by Williams, who cited a viral illness.
The pullout of the American gave a walkover into the third round for 2014 finalist Ana Ivanovic.
"I just wasn't able to get out there tonight. Every match you have to be at your best, to win," said Williams, who made her decision after pre-match warm-up. "I just couldn't be at my best today."
US Open winner Marin Cilic, the seventh seed, beat Joao Sousa 6-4, 6-2, while Spain's Feliciano Lopez stopped Canadian Milos Raonic 7-6 (7/4), 6-4 as the ninth seed lost an opening match for the second straight week.
Sam Querrey put out John Isner 6-3, 7-6 (7/3) and South African 15th seed Kevin Anderson defeated Leonardo Mayer 7-6 (7/5), 3-6, 6-1.
Controversial Nick Kyrgios was dumped out, a 6-2, 6-1 first-round victim of French 12th seed Richard Gasquet.
Kyrgios, building a reputation as the bad boy of the game, was unremarkable in his loss, which lasted for only 56 minutes.
Toronto women's champion Belinda Bencic maintained her recent giant-killing form with a battling 7-5, 6-3 win over higher-ranked German opponent Angelique Kerber.
Bencic, 18, is brimming with confidence after winning in Toronto at the weekend after a tournament which included a stunning semi-final defeat of Grand Slam-chasing world number one Serena Williams.
Elsewhere Tuesday, Sloane Stephens took down another seed as she beat number 10 Carla Suarez Navarro 6-1, 6-2.
France's Kristina Mladenovic overcame Daniela Hantuchova 6-2, 6-1; Flavia Pennetta defeated former Australian Open finalist Domenika Cibulkova 7-5, 6-2.
Mona Barthel beat Australian Casey Dellacqua in a 2-6, 6-3, 7-6 (7/4) comeback while Caroline Garcia beat Sabine Lisicki 3-6, 6-3, 6-4.
Former number one Victoria Azarenka reached the second round 6-1, 6-2 over Lauren Davis.
Results on the third day of the ATP and WTA Cincinnati Masters on Tuesday (x denotes seeded player).
Sloane Stephens (USA) bt Carla Suarez Navarro (ESP x10) 6-1, 6-2
Kristina Mladenovic (FRA) bt Daniela Hantuchova (SVK) 6-2, 6-1
Flavia Pennetta (ITA) bt Domenika Cibulkova (SVK) 7-5, 6-2
Anastasia Pavlyuchenkova (RUS) bt Roberta Vinci (ITA) 6-3, 0-6, 6-2
Daria Gavrilova (RUS) bt Sara Errani (ITA x16) 6-1, 4-6, 6-2
Victoria Azarenka (BEL) bt Lauren Davis (USA) 6-1, 6-2
Camila Giorgi (ITA) bt Christina McHale (USA) 5-7, 6-3, 6-2
Belinda Bencic (SUI) bt Angelique Kerber (GER x11) 7-5, 6-3
Caroline Garcia (FRA) bt Sabine Lisicki (GER) 3-6, 6-3, 6-4
Mona Barthel (GER) bt Casey Dellacqua (AUS) 2-6, 6-3, 7-6 (7/4)
Anna Schmiedlova (SVK) bt Agnieszka Radwanska (POL x13) 4-6, 6-3, 6-1
Ana Ivanovic (SRB x6) bt Venus Williams (USA) walkover
Richard Gasquet (FRA x12) bt Nick Kyrgios (AUS) 6-2, 6-1
Sam Querrey (USA) bt John Isner (USA x11) 6-3, 7-6 (7/3)
Tommy Robredo (ESP) bt Pablo Andujar (ESP) 3-6, 6-3, 6-1
Kevin Anderson (RSA x15) bt Leonardo Mayer (ARG) 7-6 (7/5), 3-6, 6-1
Jared Donaldson (USA) bt Nicolas Mahut (FRA) 7-5, 6-7 (2/7), 6-2
Borna Coric (CRO) bt Alexander Zverev (GER) 7-5, 3-6, 7-6 (7/5)
Jeremy Chardy (FRA) bt Rajeev Ram (USA) 6-4, 6-2
Fernando Verdasco (ESP) bt Jo-Wilfried Tsonga (FRA) 4-6, 6-3, 6-4
Feliciano Lopez (ESP) bt Milos Raonic (CAN x9) 7-6 (7/4), 6-4
Marin Cilic (CRO x7) bt Joao Sousa (POR) 6-4, 6-2
Alexandr Dolgopolov (UKR) bt Bernard Tomic (AUS) 6-4, 6-1
Grigor Dimitrov (BUL x16) bt Vasek Pospisil (CAN) 7-6 (7/4), 7-6 (7/5)
Roger Federer (SUI x2) bt Roberto Bautista Agut (ESP) 6-4, 6-4