That isn't really surprising considering that they are two of only five players remaining with more than one Grand Slam title. But with that experience comes pressure, and both have been feeling it for years.
"I (am) almost 25, but seems like I am playing for 100 years here on the tour," Nadal said with a laugh after easily eliminating Croatian wild card Antonio Veic 6-1, 6-3, 6-0 in the third round. "In my opinion, tennis is a very demanding sport mentally and physically." Sharapova, who faced little trouble in beating Chan Yung-jan of Taiwan 6-2, 6-3, agreed with that assessment.
"We've done this for almost all our lives," said Sharapova, who turned professional when she was 14, "so we feel like we're on this sort of hamster carousel and we just keep going." Novak Djokovic also advanced to the fourth round, completing a suspended match against Juan Martin del Potro, while Andy Murray won despite twisting an ankle and said he would decide later on his prospects of continuing in the tournament.
On Sunday, Djokovic is to again put his perfect season on the line, while 2009 French Open champion Roger Federer plays Davis Cup teammate Stanislas Wawrinka. On the women's side, defending champion Francesca Schiavone is scheduled to be in action.
Nadal came into the French Open after losing to Djokovic in two clay-court finals, but he still is the favorite for many observers.
The pressure showed in the first round, when the top-ranked Spaniard was pushed to five sets by John Isner.
He also had a slight struggle in the second round, but in Saturday's match Nadal looked more like the player who is trying to equal Bjorn Borg's record of six titles at Roland Garros.
"I did a few things much better than the previous days.
Happy for that," said Nadal, who is 41-1 at the clay-court major. "Just the beginning of the second, for moments of the second set, I had a few more mistakes. But for the rest of the match, I started to have better control of the ball." Sharapova also has been troubled in the early rounds. She trailed by a set and 4-1 in the second round against French wild card Caroline Garcia before advancing.
"I was just really happy to come back from that, from the position that I was in," Sharapova said before downplaying the importance of the come-from-behind victory. "I certainly wasn't thinking, 'Oh, if I come back in this match and I end up winning it's going to give me so much confidence."' Murray had his scariest moment so far in the third round of his 6-2, 6-3, 6-2 win over Michael Berrer.
The three-time Grand Slam runner-up twisted his right ankle while going for a ball early in the second set. After getting his foot taped by a trainer, he came back on court and immediately converted his break point.
But his status for the rest of the tournament is now in jeopardy.
"I've managed to play almost two sets with it but I've just got to wait and see and do all the right things," Murray said. "I'll try to hit some balls tomorrow and that's all I can do just now. I don't know if I'll be playing the next match. I don't know if I'll be 100 per cent fit."