Maria Sharapova set up a match against Eugenie Bouchard with a first-round win at the Madrid Open on Sunday.
Canadian Bouchard called Sharapova “a cheater” prior to the Russian’s return to competitive action in April after a 15-month doping ban.
Bouchard, who beat Alize Cornet on Saturday, believes the five-time Grand Slam winner should be banned for life.
Sharapova beat Croat Mirjana Lucic-Baroni 4-6 6-4 6-0, which comes after reaching the semi-finals in Stuttgart.
The 30-year-old, who won this tournament in 2014, will take on world number 59 Bouchard on Monday.
In October 2016, the Court of Arbitration for Sport said Sharapova was not an “intentional doper”.
“When you’re out of the game for a long time you just want to play as many games as possible,” said Sharapova.
World number two Angelique Kerber eased into round two with a convincing 6-4 6-2 win over Hungary’s Timea Babos.
The German is the top seed in the draw with world number one Serena Williams absent because the 23-time Grand Slam champion is expecting her first child.
Kerber’s form has been inconsistent this season, but she was rarely troubled in wrapping up victory in just over an hour on court.
Sharapova’s conqueror in Stuttgart, Kristina Mladenovic, is also safely through after Croat Ana Konjuh retired when the French world number 17 levelled at one set all.
Russian eighth seed Svetlana Kuznetsova, a 2015 finalist in Madrid, cruised past compatriot Yaroslava Shvedova 6-4, 6-3.