In the past 12 months, Maria Sharapova has beaten just about everyone apart from Serena Williams.

In fact, the Russian has not beaten Williams since 2004 so, as she continues her French Open title defence in Paris, Sharapova will doubtless be grateful she can't play the American until the final.

Tomorrow, though, Sharapova will play the woman the United States hopes will be the next Serena, Sloane Stephens.

Having crushed the 20-year-old in Rome a couple of weeks ago, Sharapova will not go into their fourth-round match with any undue anxiety.

But the world No 2 knows Stephens has the talent and the confidence to believe she can repeat the kind of heroics she showed in Australia at the start of the year, when she beat Williams on her way to the semi-finals.

"It was a couple of weeks ago that we played, but this is a Grand Slam," Sharapova said. "I'm sure she will want to change a few things around and play a better match and you expect that at this type of tournament. There is no doubt that I have a tough one ahead of me."

Stephens booked her meeting with Sharapova thanks to a 6-4, 6-7, 6-3 win over Marina Erakovic, the New Zealander, who beat Scotland's Elena Baltacha in round one. The American reached the last 16 at Roland Garros last year and seems to save her best for the majors.

"Leaving here last year I never thought I would make the semis of a Grand Slam and have done all these great things, being in this position I am now, top 20 and all this other stuff," Stephens said.

An elegant mover and superb athlete, Stephens has shrugged off a poor run of form – during which she has been uncharacteristically grumpy off-court – and does not lack confidence.

"This is my favourite tournament, so I would really, really, really love to win it," she said. "But that's a long shot.

"I think every Grand Slam I'm getting closer and closer. You've just got to keep plugging away and hopefully, eventually, I'll have that big trophy."

Yesterday, Sharapova found herself 4-1 down in the second set against Jie Zheng of China, but turned things round in time to record a 6-1, 7-5 victory, despite a dodgy line call, not the first at this year's event.

The French Open is the only one of the four Grand Slam events not to use Hawk-Eye technology, the electronic line-calling system that allows players to make up to three challenges per set.

The theory behind not using it on clay is that the ball leaves a mark, but it is not a perfect science; sometimes the ball does not leave a full mark and sometimes the umpire, when called upon to check it, picks the wrong mark.

Serving at 1-3 in the second set, Sharapova was livid when Emmanuel Joseph called a double fault, handing Jie the break, because, she said, he was pointing to the wrong mark.

"The umpire did not recognise that the mark he pointed out was about a foot away from the actual mark," Sharapova said. "So that's a huge question mark to begin with.

"All the other Grand Slams have Hawk-Eye. I know these types of situations happen, although much more rarely on the clay. So why not have it here? Why don't we have a system like this? Is it a money concern? I don't think so.

"This is just absolute proof that it's a big point and it can happen in any situation. I hope the umpire is able to acknowledge that it was not the right thing to say."

Third seed Victoria Azarenka was below her best, but battled past Alize Cornet of France 4-6, 6-3, 6-1 while former champion Francesca Schiavone upset home favourite Marion Bartoli 6-2, 6-1.