The former world number one was controversially handed a wildcard into the claycourt event after her suspension wiped out her ranking.

If Sharapova gets through her opener on Wednesday -- the first day she is eligible to play -- against the 34-year-old Vinci, she could face Poland's Agnieszka Radwanska, one of her fiercest critics, in the second round.

Radwanska, who starts against Russia's Ekaterina Makarova, blasted Sharapova in an interview on Friday when she insisted that the sport's poster girl should not be awarded wild cards after her doping ban.

"This kind of entry (wild cards) into the tournament should apply to players who dropped in the ranking because of injury, illness or some other random event. Not for those suspended for doping. Maria should recover some other way, starting with smaller events," Radwanska said.

"So far she hasn't been invited to slams in Paris (French Open) and London (Wimbledon) and in my opinion that's how it should remain. She should win her spot by playing well."

Sharapova was banned for two years after testing positive for meldonium at the 2016 Australian Open but had her suspension cut to 15 months on appeal.

The Russian turned 30 on April 19, but on the Stuttgart tournament's website she describes her return as her "nicest present. I'm getting my sport back."