Roger Federer is to take a late decision over continuing at the Internazionali d'Italia after starting his tournament with a straight-sets win over Mischa Zverev.
The Swiss maestro withdrew from Madrid last week with a troublesome back and has been beset by injury problems this season, including undergoing knee surgery.
After beating Zverev in Rome, Federer revealed he only decided to play the match upon completing the warm-up.
The third seed is scheduled to play Dominic Thiem in round three on Thursday, but the 17-time grand slam champion remains unsure as to whether he will be fit to play.
"I played cautious and I only decided after the warm-up that I was actually going to play," he said. "So for me it was a big match on many levels.
"I was expecting to lose in straight sets. That was the mind set going in, so to win in straights is actually a really big surprise to me.
"In terms of information, looking ahead for the next few weeks, regardless if I'm going to play tomorrow or not, this was something I feel like I needed to do to get a sense of where I'm at.
"It would have been easy not to play and then just be unsure how I was going to feel in Paris [for the French Open].
"So at some point you have to go out there and see how it feels, and I'm happy I was able to play a full match without any setbacks.
"I don't know how I'm going to feel tomorrow. It's baby steps right now. So to even think of tomorrow is already a big ask."