Bouchard (L) shakes hands with Sharapova after the second-round match at the Madrid Open in Spain on May 8, 2017. [Photo/Agencies]

Sharapova won the first game with a powerful shot straight at Bouchard's body at the net, forcing Bouchard to protect herself. The Canadian deflected the ball with her racket and lost the point.

In a tense game near the end of the first set, Sharapova was frustrated after Bouchard won a point with a ball that changed directions from a net cord. Bouchard turned around without directly apologizing.

Earlier, top-seeded Angelique Kerber defeated Katerina Siniakova of the Czech Republic 6-2, 1-6, 7-5 to advance and regain the world No 1 ranking.

Second-seeded Karolina Pliskova, ranked third in the world, lost to Anastasija Sevastova of Latvia 6-3, 6-3, ending her hopes of reaching No 1 this week.

That meant Kerber was guaranteed to retake the top ranking from Serena Williams next week. Kerber will face Bouchard next.

On the men's side, Tomas Berdych defeated Denis Istomin of Uzbekistan 6-4, 6-4, while Grigor Dimitrov of Bulgaria beat Philipp Kohlschreiber of Germany 7-6 (7), 6-4.

Nick Kyrgios, Gilles Simon, and David Ferrer also progressed.

AP