After showing a few signs of weakness, Rafael Nadal appears to be back on track as he heads into Wednesday’s quarterfinals of the French Open at Roland Garros.

Celebrating his 27th birthday, Nadal won his first straight-set match against No. 13 Kei Nishikori 6-4, 6-1, 6-3, shaking off the two four-setters in the opening rounds, and an early scare from No. 27 Fabio Fognini in the third round.

The seven-time French Open champ has now reached his ninth quarterfinals this season, and will face Switzerland’s Stanislas Wawrinka for the second time this year. Nadal has the potential to be the first player to ever win the same major eight times.

Nadal crushed Wawrinka in the finals in Madrid last month, and the Swiss star could have weakened legs after a five set marathon against No. 7 Richard Gasquet in the fourth round.

Nadal has won every meeting between the two, and victory would slot him in the semifinals against either No. 1 Novak Djokovic or No. 12 Tommy Haas.

Haas was up two sets on No. 19 John Isner in the third round, before letting up the next two and finally putting the American away in five. The 35-year-old followed that victory with a straight set performance over Mikhail Youzhny and now meets Djokovic, who has lost one set in Paris.

The Serb had gave up the first set 4-6 to No. 16 Philipp Kohlschreiber, but then took the next three 6-3, 6-4, 6-4. Djokovic is now 28-4 this year, including a victory over the streaking Nadal in the finals in Monte Carlo back in April.

TV coverage by ESPN2 began at 8 a.m. Eastern, or watch a live online stream at Watch ESPN here.

Prediction: Nadal over Wawrinka in four sets, and Djokovic should sweep the older Haas.