STUTTGART, Germany (AP) Seeded players Gael Monfils and Viktor Troicki were made to fight hard to reach the Mercedes Cup quarterfinals on Wednesday.
The fourth-seeded Monfils of France fired 18 aces and defeated Andreas Haider-Maurer of Austria 7-6 (6), 7-6 (5), while the eighth-seeded Troicki beat German wild card Alexander Zverev 6-3, 6-7 (6), 6-3.
The Serb next faces Sam Groth of Austria or the third-seeded Feliciano Lopez of Spain, playing late Wednesday.
Monfils awaits Poland's Jerzy Janowicz or sixth-seeded German Philipp Kohlschreiber, also playing late.
Rafael Nadal was top-seeded for the event, which was on grass for the first time.