Cilic, the 2014 champion, continued his hard court season surge with a 6-1 6-2 6-3 rout of Sergiy Stakhovsky of Ukraine to reach a showdown match against American Jack Sock.
"I played really well today from the start till the end," the 27-year-old Croat told reporters. "I didn't have too many ups and downs in the game.
"I felt that I was controlling the match. I felt that I was really mixing up the game well."
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Cilic, who recently made a coaching switch away from former Wimbledon champion Goran Ivanisevic, began to put his big-hitting game in gear during the grass court season and has built momentum since.
He reached the semi-finals at Queen's Club, where he lost to Andy Murray, and followed that with a trip to the quarter-finals before falling to Roger Federer.
This summer he won his first ATP Masters 1000 event in Cincinnati, beating Murray in the final to end the Scotsman's 22-match winning streak that included his Wimbledon and Olympic triumphs.
Cilic took 100 minutes to eliminate Stakhovsky, facing only two break points in the romp.
"I think that was really, really, high-quality match," he said.
Cilic expects a tougher test against Sock, who came from two sets down to beat him in a five-setter in this summer's Davis Cup matches in Portland, Oregon.
"I'm definitely expecting a tough match-up. Jack can be very dangerous on the court," Cilic said about the 26th-seeded American.
"He's athletic guy. He can run down many balls. In the U.S., I guess that he plays even a bit better. He gets inspired with the crowd.
"Hopefully I can keep my level."
(Editing by Steve Keating)
