Belgian Elise Mertens sent American third seed Jessica Pegula crashing out of the French Open with a comprehensive victory in the last 32 on Friday.

The 28th seed cruised to a 6-1, 6-3 victory on Court Philippe Chatrier to reach the fourth round for the third time.

World number three Pegula, who only has two WTA Tour titles to her name, has still never passed the quarter-final stage of a Grand Slam tournament.

"I'm very happy to win in two sets. She's a very good player," said Mertens.

The former Australian Open semi-finalist will next face the winner of an all-Russian tie between Anastasia Potapova and Anastasia Pavlyuchenkova.

Mertens raced through a one-sided first set before Pegula raised her level in the second.

The players traded breaks early on before Mertens struck again for a 4-3 lead.

She then saved three break points to move within one game of victory and quickly closed it out on her first match point.