Top-seeded Rafael Nadal opened his Rogers Cup title defense Wednesday, beating England's Daniel Evans 7-6 (6), 6-4 in a second-round match delayed by rain three times.

After rain delays of six and 30 minutes, Nadal fought off two set points in the first-set tiebreaker. Play was stopped for 1 hour, 56 minutes with Nadal leading 2-0 in the second set.

"All the matches are difficult here," Nadal said. "It was a tough first set. Then in the second, I was able to take advantage at the beginning, but then he broke me back."

The 33-year-old Spanish star, a four-time Rogers Cup champion, will face Argentina's Guido Pella in the third round. Pella beat Moldova's Radu Albot 6-3, 2-6, 7-6 (2).

Second-seeded Dominic Thiem beat Canada's Denis Shapovalov 6-4, 3-6, 6-3. Coming off a victory on clay at the Generali Open in his native Austria, Theim will face 14th-seeded Marin Cilic of Croatia,

Cilic topped Australia's John Millman 6-3, 6-4.

Felix Auger-Aliassime won an all-Canadian match when Milos Raonic retired because of a back injury. Auger-Aliassime won the first set 6-3, and Raonic took the second 6-3 before stopping play.

Poland's Hubert Hurkacz upset fourth-seeded Stefanos Tsitsipas of Greece 6-4, 3-6, 6-3, France's Richard Gasquet beat fifth-seeded Kei Nishikori of Japan 6-7 (6), 6-2, 7-6 (4); France's Adrian Mannarino, topped 11th-seeded Borna Coric of Croatia, 6-2, 6-1; ; and Cristian Garin of Chile knocked off 12th-seeded American John Isner 6-3, 6-4.

Sixth-seeded Karen Khachanov of Russia edged Stan Wawrinka of Switzerland 6-4, 6-7 (3), 6-2; seventh-seeded Fabio Fognini beat American qualifier Tommy Paul 7-6 (3), 6-3; eighth-seeded Daniil Medvedev of Russia topped Kyle Edmund of Britain 6-3, 6-0; and 10th-seeded Roberto Bautista Agut of Spain edged Diego Schwartzman of Argentina 6-2, 7-5.

Serena Williams won her first match since losing the Wimbledon final, beating Elise Mertens of Belgium 6-3, 6-3 on Wednesday night in the second round of the Rogers Cup.

The 37-year-old Williams has won the event three times, all in Toronto, and has a 31-4 match record.

"I feel like my movement is great — been working on my fitness, so I felt like it really was able to shine through today," Williams said. "I'm loving going out there, and I'm loving kind of running. So it's a good thing."

In the third round, she'll face Russia's Ekaterina Alexandrova — a 6-4, 6-3 winner over Zhang Shuai of China.

"Now that I'm just injury-free, I'm just enjoying being able to train, and I haven't been able to do it since January, really," said Williams, seeded eighth. "So I just think that the fact that I can train and practice and get in the gym is really going to be helpful for me."

Wimbledon champion Simona Halep of Romania beat American qualifier Jennifer Brady 4-6, 7-5, 7-6 (5).

The winner last year in Montreal, Halep lost a 4-0 lead in the third set when Brady won five straight games. Halep broke Brady for the third time in the set to go up 6-5, but Brady broke back to force the tiebreaker.

"It was a very, very tough one," Halep said. "I expected it because I knew that she's going to serve big and also the forehand is big. I didn't feel 100% ready for the tournament because I had a long break (after Wimbledon). But I'm really pleased with the way it was today, the fact that I fought till the end."

The 26-year-old Halep will face Svetlana Kuznetsova of Russia. Kuznetsova beat Donna Vekic of Croatia 7-6 (4), 6-3.

Second-ranked Naomi Osaka of Japan reached the third round when German qualifier retired because of a left abdominal injury. Osaka led 6-2 in her first match since losing in the first round at Wimbledon.

Canada's Bianca Andreescu beat Russia's Daria Kasatkina 5-7, 6-2, 7-5. On Tuesday night, the 19-year-old Andreescu beat fellow Canadian Eugenie Bouchard.

Third-ranked Karolina Pliskova of the Czech Republic also advanced, beating American qualifier Alison Riske 6-4, 6-7 (4), 6-2

Poland's Iga Swiatek beat 15th-seeded Caroline Wozniacki 1-6, 6-3, 6-4 in the late match. Swiatek will face Osaka.

No. 16 seed Anett Kontaveit of Estonia reached the third round when Carla Suarez Navarro of Spain retired with a hip injury while trailing 7-5, 3-1. Kontaveit will play Pliskova.

Victoria Azarenka of Belarus was eliminated, falling 7-5, 7-5 to Dayana Yastremska of Ukraine.

Ukraine's Elina Svitolina, the 2017 Rogers Cup winner, moved onto the third round with a 6-3, 3-6, 6-3 victory over Katerina Siniakova, and 2015 champion Belinda Bencic of Switzerland edged Julia Goerges 5-7, 6-3, 6-4. Bencic and Svitolina will face each other Thursday.