STUTTGART, Germany (AP) Top-seeded Rafael Nadal overcame stiff resistance from Bernard Tomic to reach the semifinals of the Mercedes Cup with a 6-4, 6-7 (6), 6-3 victory on Friday.
Nadal will next play fourth-seeded Gael Monfils, who beat Philipp Kohlschreiber 7-5, 3-6, 6-3.
Also, second-seeded Marin CIlic served 19 aces to rally past qualifier Mischa Zverev 4-6, 7-6 (5), 7-6 (5) to set up a semifinal against eighth-seeded Viktor Troicki, who beat Sam Groth 7-6 (3), 6-1.
The tournament is a grass-court tune-up for Wimbledon and Nadal said he was pleased with his game. After needing 2 hours, 40 minutes to beat Marcos Baghdatis on Thursday, Nadal was stretched again a day later, staying on court for 2 hours, 20 minutes.
''I played better than yesterday. This is probably his favorite surface so it's a great victory for me,'' Nadal said.
Nadal seized the early momentum in the third set by taking a 3-0 lead to finish off the fifth-seeded Tomic.
Cilic, the U.S. Open champion, took advantage of a pair of mistakes by Zverev in the tiebreakers. Zverev committed his only double-fault to give Cilic two set points in the first and let a shot go that landed inside the line in the second, giving Cilic two match points. On both occasions, Cilic used his second opportunity.
Troicki withstood 13 aces from Groth, who also had seven double-faults.