The lanky Russian, who only recently returned to the tour following a lengthy break for shoulder surgery, was given a tough workout by Viktoriya Kutuzova, of Ukraine.
Sharapova won 7-5, 6-4, but it took her the best part of 1hr ¾, and for much of the first set it looked as if the 2004 champion would be making an early exit from Wimbledon.
"I think there's still work to be done," Sharapova said afterwards. "I think all the matches that I've been playing have really helped me, not just with my tennis but physically too, getting used to the movement on the court. But I always feel like I move pretty good on grass."
That may be true, but like a rusty machine, Sharapova was slow to get started and never really found a reliable rhythm.
Kutuzova, a 20-year-old from Odessa ranked No 79 (and who has never been higher than No 76) served for a 5-1 lead in the first set, and her eminent opponent seemed unable to put together a convincing run of winners.
Unsurprisingly, though, the Ukrainian tightened up on her serve, double-faulting and allowing Sharapova a way into the match.
Kutuzova proved that she is no pushover, though, hitting the ball deep, with power, and forcing the Florida-based Russian to work hard to secure the first set after almost an hour.
The players are remarkably similar, not only physically but aurally. Kutuzova, who had come through three matches in the qualifying tournament, looks like a 90 per cent scale model of Sharapova, but the sound-effects are 100 per cent accurate: grunt for grunt, these two gave it all they had.
The second set demonstrated, as if it needed proof, that who is serving is practically irrelevant in contemporary women's matches at Wimbledon. In the latter stages of this match, serve was a contra-indicator of progress, as breaks were considerably more frequent than holds.
Sharapova eventually pulled herself together to close out the match, but she has had to reconstruct her service action following the surgery and her delivery is no longer the weapon it once was.
Repairs to a rotator cuff sound like remedial work on an element of the Sharapova wardrobe, but in medical terms it means shoulder surgery that necessitated a nine-month lay-off from the game. She no longer wears the heavy dressing that she sported on her return to action in Warsaw a month ago, but clearly Sharapova is yet to return to full physical confidence.
"It's funny, because sometimes in the middle of the match I'll find myself thinking: 'The progression of the shoulder: How's it feeling'? But I think it's just a matter of forgetting about it and just playing," she said.
Easier said than done. Sharapova seemed tentative in her movement around the court, understandably perhaps as she twice lost her footing and landed up in an ungainly heap behind the service line before returning, gingerly, to her feet.
Both times Sharapova was applauded as she rose: the Wimbledon crowd have already lost one champion to injury in Rafael Nadal, and they are clearly aware that the tournament's remaining talents must be cherished.
Sharapova will no doubt be the better for this match, as her confidence grows and her serve starts to find its groove. But she will need to be, because this was a far from assured performance.
But unlike Nadal, she is here, and playing, and over the first hurdle. For that she is grateful, as are her fans. "I've said, and I'll say it again, I'm so thankful. If someone told me four months ago that I'd be here playing Wimbledon, I wouldn't be surprised, but I would be really happy about the fact. And I am happy to be here."