The move came immediately after Williams lost in straight
sets to Nadia Podoroska at the Italian Open on Wednesday in her first match in
nearly three months.
"Maybe I do need a few more matches, so I'm going to
try to figure that out with my coach and my team and see what we would like to
do," Williams said after losing to Podoroska, a semifinalist at last
year's French Open.
"I have been training for months, but it feels
definitely different on clay to make that last adjustment."
Williams is preparing for the French Open, which starts at
the end of the month.
Venus Williams, Serena's sister, also accepted a wild-card
invitation, organisers said.
The clay-court event in Parma, which was added to the
calendar amid the coronavirus pandemic, starts on Sunday.