Second-seeded Marin Cilic of Croatia reached the World Tennis Tournament quarterfinals with a 7-6 (7-2) 7-6 (9-7) second-round win against Gilles Muller of Luxembourg.

Neither player faced a break-point in the first set, but Muller saved five in the second.

Cilic had two match points at 6-4 in the tiebreak, but then saved a set point at 7-6 down as Muller fought back strongly.

The 2014 US Open champion next plays Philipp Kohlschreiber, who won 6-4 6-2 against qualifier Ivan Dodig of Croatia.