Grigor Dimitrov battled past Lukas Rosol at the Western and Southern Open, winning in three sets on Sunday.

The Bulgarian 16th seed has been in inconsistent form during the North American hard-court swing, but posted a 6-2 3-6 6-3 victory over Rosol.

Dimitrov broke serve three times during his win, which came in one hour, 25 minutes at the ATP 1000 event in Cincinnati.

He had rolled into a 4-0 lead on his way to taking the first set easily, before being broken in the sixth game of the second as Rosol levelled the contest.

Dimitrov only need one break in the third, and it also came in the sixth game, as he claimed a deserved win.

Awaiting him in the second round is either Canadian Vasek Pospisil or American Denis Kudla.

The only other main-draw match on Sunday saw Martin Klizan edge Austrian Dominic Thiem 7-6 (7-5) 3-6 7-6 (7-4).

Slovakian Klizan served 16 aces and 10 double faults and managed just one break of serve, while Thiem wasted nine of his 12 break-point chances.

Thiem won 51 return points to Klizan's 26, won 12 more points during the three-setter and led 3-1 in the deciding set, but still suffered defeat.