It was Cilic's fourth victory over Sijsling in as many encounters and the Croatian was dominant from the start. Playing steadily from the baseline, he took a 5-2 lead in the first set before Sijsling leveled for 5-5. Cilic then broke in the 12th game on his second set point.
Cilic, who won the tournament in 2012 and reached the 2011 final, broke again at 3-2 in the second set before easily finishing off the match.
"It is good that I won in two sets, conditions here are tough with humidity and heat," Cilic said. "I have adjusted well to the conditions, but winning as fast as possible is always recommended."
Fifth-seeded Czech Lukas Rosol also reached the quarterfinals, defeating Spaniard Pere Riba 7-6 (4), 6-1.
Spain's Pablo Carreno Busta advanced by walkover after eighth-seeded Carlos Berlocq of Argentina withdrew because of an injury.
- Sports & Recreation
- Marin Cilic
- Igor Sijsling