Top-seeded Novak Djokovic recorded eight aces while defeating fellow Serbian Filip Krajinovic 7-6 (6), 6-3 in the opening round of the Erste Bank Open in Vienna, Austria.
Djokovic delivered 39 winners in his first appearance at the event since winning the title in 2007. Home-country favorite Dominic Thiem, the second seed, also prevailed in straight sets, posting a 6-4, 7-5 triumph over Vitaliy Sachko of Ukraine.
In other matches, Chile's Cristian Garin defeated Switzerland's Stan Wawrinka 6-4, 6-7 (9), 6-3, and Bulgaria's Grigor Dimitrov notched a 7-6 (6), 6-3 victory over Russian Karen Khachanov. Poland's Hubert Hurkacz, Great Britain's Daniel Evans and Italy's Lorenzo Sonego also advanced.
The Czech Republic's Jiri Vesely fired nine aces while stunning fifth-seeded American Tennys Sandgren 6-4, 7-6 (7) in a first-round match at Nur-Sultan, Kazakhstan.
Sandgren had 13 aces and converted 36 of 43 first-service points in defeat. Vesely next plays Egor Gerasimov after the Belarusian outlasted South Africa's Lloyd Harris 6-3, 3-6, 7-6 (3).
In other matches, Italian qualifier Andreas Seppi defeated Russian qualifier Aslan Karatsev 6-3, 1-6, 6-3; Japan's Yuichi Sugita knocked off Bosnia's Damir Dzumhur 6-1, 5-7, 6-4 in a battle of qualifiers; and Finland qualifier Emil Ruusuvuori was a 6-2, 6-0 winner over Kazakhstan wild-card entrant Timofey Skatov.
--Field Level Media