Fellow Croatian Ivo Karlovic also used his serve to great effect, losing only eight points on his delivery in a 6-4 6-1 victory over wildcard Stefan Kozlov.
World number seven Cilic failed to convert any of three set points in the opening set tiebreak against Serb Tipsarevic, but took four straight games from 2-2 in the second set to level.He then broke early in the deciding set and held firm.
“It’s never easy, especially the first match on grass,” Cilic told the ATP’s website. “Janko has been at the top of the tennis game and is a quality player.”
Cilic will seek a 50th career grasscourt victory on Friday when he plays Canada’s Vasek Pospisil, who was leading Alexandr Dolgopolov when his opponent retired.
“I’m playing way, way better than at the start of the year and my claycourt game helped me to get into the right hitting zone,” said Cilic. “Having strong mental toughness, which you need on clay, also gives me confidence.”
The 38-year-old Karlovic said he has been sharpening his lawn game for more than a week.
“It was good as I was here preparing here for the past seven days,” he said. “I’m happy with the way I performed.”
He will now play Russia’s Daniil Medvedev, who beat fellow 21-year-old Thanasi Kokkinakis.
Dimitrov crashes out of Stuttgart Open
Second seed Grigor Dimitrov slumped to a 7-6 (4) 6-3 loss to world number 155 Jerzy Janowicz at the Stuttgart Open, with the Pole booking a surprise quarter-final spot. Janowicz made the most of momentary lapses in concentration by Dimitrov, who followed top seed Roger Federer, beaten by Tommy Haas on Wednesday, out of the Wimbledon warmup event.
A sensational backhand down the line – the shot of the match – gave Janowicz the minibreak he needed in the first set tiebreak. Another whipping forehand earned Janowicz, a former world number 14 who has been plagued by injuries in recent seasons, his first two break points on Dimitrov’s serve. The Bulgarian then sent one of his forehands long to allow his opponent to serve out the match.