Toronto - World No 1 Serena Williams rallied to advance to the third round of the WTA Rogers Cup on Tuesday by defeating Italy's Flavia Pennetta 2-6, 6-3, 6-0.
It was the 725th career match triumph for Williams, who withdrew from last week's Stanford event with a right elbow injury but launched her US Open hardcourt warm-up campaign successfully.
"The elbow was okay - definitely not perfect, but I'll see how it recovers tomorrow," Williams said.
"It was a good opportunity for me because I hadn't played a match on hardcourts since April-ish, early, early April, after Miami. It was a long time ago."
Williams, winner of the past four Grand Slam events, took 98 minutes to capture her first match since winning at Wimbledon, and as she did during much of her title run in London, she did it after dropping the first set.
In the first set, Williams connected on only 44 percent of her first serves, won just 7 of 12 first serve points and only 2 of 15 on her second serve. She was broken four times, twice more than Pennetta.
"Unforced errors, you know, pretty much. I had a lot of unforced errors," Williams said. "I just told myself to drop it, like drop the racquet low and get ready to do everything I could to get into the game and to try to do different things, and that's what I started doing out there.
"I was thinking, 'The last time I was here I won. I should at least try to get through this and give 200 percent, and I started playing better. I was still making errors, but I just started playing better and making less errors."
Williams held at love to open the second set but surrendered a break to fall behind 2-1 before storming back to win 11 of the last 12 games and roll to her seventh victory in as many starts against Pennetta.
Williams became the only player to reach the third round at the US Open hardcourt tune-up event thanks to rain that washed out all but two matches on Monday. Her next match will be Thursday.
Williams could complete a calendar-year Grand Slam with a victory at the US Open, which begins August 31, and claim her 22nd career Grand Slam title, matching Steffi Graf's Open Era record total.
This week, Williams hopes to win in Toronto for a third time in a row after 2011 and 2013 titles in the Canadian event, which exchanges venues every year with a men's event being played this week in Montreal.
Results on Tuesday from the second day of the WTA Rogers Cup (x denotes seed):
Second round
Serena Williams (USA x1) bt Flavia Pennetta (ITA) 2-6, 6-3, 6-0
First round
Daria Gavrilova (RUS) bt Samantha Stosur (AUS) 6-4, 6-4
Ekaterina Makarova (RUS x11) bt Anna Tatishvili (USA) 6-3, 6-3
Roberta Vinci (ITA) bt Karin Knapp (ITA) 6-0, 6-0
Mirjana Lucic-Baroni (CRO) bt Karolina Plishkova (CZE x10) 3-6, 7-6 (7/5), 6-2
Barbora Strycova (CZE) bt Varvara Lepchenko (USA) 6-2, 6-4
Polona Hercog (SLO) bt Alison Van Uytvanck (BEL) 6-4, 1-6, 6-3
Jelena Jankovic (SRB) bt Caroline Garcia (FRA) 7-6 (7/4), 6-2
Angelique Kerber (GER x13) bt Misaki Doi (JPN) 6-0, 6-1
Alize Cornet (FRA) bt Carla Suarez Navarro (ESP x9) 6-3, 6-7 (2/7), 6-4
Carina Witthoeft (GER) bt CoCo Vandeweghe (USA) 6-3, 3-6, 6-1
Lesia Tsurenko (UKR) bt Yanina Wickmayer (GER) 6-3, 7-6 (7/3)
Monica Puig (PUR) bt Mariana Duque-Marino (COL) 6-4, 4-6, 7-5
Victoria Azarenka (BLR) bt Elina Svitolina (UKR) 6-1, 6-4
Sara Errani (ITA x15) bt Kristina Mladenovic (FRA) 5-7, 6-1, 6-0
Julia Goerges (GER) bt Zarina Diyas (KAZ) 2-6, 6-1, 7-5
Alison Riske (USA) bt Timea Bacsinszky (SUI x12) 3-6, 7-6 (7/4), 7-6 (7/3)
Madison Brengle (USA) bt Carol Zhao (CAN) 6-1, 6-1
Olga Govortsova (BLR) bt Irina-Camelia Begu (ROM) 6-3, 7-6 (7/4)
Andrea Petkovic (GER x16) bt Francoise Abanda (CAN) 3-6, 6-4, 6-2
Belinda Bencic (SUI) bt Eugenie Bouchard (CAN) 6-0, 5-7, 6-2
Heather Watson (GBR) bt Irina Falconi (USA) 6-1, 6-2
Dominika Cibulkova (SVK) bt Sloane Stephens (USA) 6-3, 6-4