Updated

An injured Victoria Azarenka reached the second round, while former French Open runner-up Sara Errani was a stunning opening-round loser Monday on opening day at Wimbledon.

The second-seeded former world No. 1 Azarenka whipped Portugal's Maria Joao Koehler 6-1, 6-2 on Court 1 on the grass at the storied All England Club.

The Australian Open champion and U.S. Open runner-up Azarenka suffered a knee injury while up a set and 1-0 in the second.

The Belarusian star, who is no stranger to injury drama, wound up doing a split behind the baseline at one point and injured her right knee, which wound up requiring treatment on three occasions. When the injury occurred, Azarenka was laying on the court crying and screaming.

Azarenka hobbled around the court a bit after the injury, but had no problem advancing.

Her second-round opponent will be former top-10 player Flavia Pennetta of Italy.

Earlier on Day 1, it didn't take long for the first upset to occur, as Puerto Rico's Monica Puig ousted the fifth-seeded Errani at the year's third Grand Slam event.

Puig claimed a 6-3, 6-2 victory over Errani, who has not had much success on the Wimbledon grass. The Italian was making her sixth visit and has never been past the third round. Clay is clearly her favorite surface, evidenced by a surprise run to the final at last year's French Open and a semifinal appearance at Roland Garros earlier this month.

This is the first Wimbledon appearance for the 19-year-old Puig, who reached the third round at the French Open.

Serbia's Ana Ivanovic battled through a tough first set against Frenchwoman Virginie Razzano, then rolled in the second to complete a 7-6 (7-1), 6-0 triumph. The former world No. 1 and former French Open champion, seeded 12th this year, has advanced past the fourth round just once in eight previous Wimbledon visits -- a semifinal run in 2007.

Meanwhile, 19th-seeded Carla Suarez Navarro drubbed fellow Spaniard Lourdes Dominguez Lino 6-2, 6-2; 22nd-seeded Romanian Sorana Cirstea subdued Swiss Stefanie Voegele 7-5, 7-6 (7-3); Czech Eva Birnerova upended 26th-seeded American Varvara Lepchenko 6-2, 4-6, 6-4; 27th-seeded Czech Lucie Safarova leveled American Lauren Davis 6-4, 6-0; and 29th-seeded Frenchwoman Alize Cornet overcame American Vania King 4-6, 6-3, 6-1.