Grigor Dimitrov reached the Australian Open second round with a straight-set win over Austrian Dennis Novak.

Dimitrov, 26, won 6-3 6-2 6-2 in one hour 38 minutes on Rod Laver Arena.

“I just tried to be compact, focused, used every opportunity I had and tried to save some energy,” said the Bulgarian, a semi-finalist last year.

Eighth seed Jack Sock lost 6-1 7-6 (7-4) 5-7 6-3 to Yuichi Sugita as 10 of 12 Americans lost in the men’s and women’s singles on day one in Melbourne.

John Isner, the 16th seed, was among the casualties, going down 6-4 3-6 6-3 6-3 to Australia’s Matthew Ebden.

Canadian 18-year-old Denis Shapovalov reached the second round, seeing off Greece’s Stefanos Tsitsipas 6-1 6-3 7-6 (7-5).

Russian Andrey Rublev, 20, outlasted Spanish veteran David Ferrer to win 7-5 6-7 (8-10) 6-2 6-7 (8-10) 6-2, while Croatia’s sixth seed Marin Cilic beat Canadian qualifier Vasek Pospisil 6-2 6-2 4-6 7-6 (7-5).

• Live scores and results
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