Dominic Thiem coasted to his first indoor title with an emphatic straight-sets defeat of Martin Klizan at the St. Petersburg Open.

The top seed took just 68 minutes to seal a third tournament victory of the year, beating Klizan 6-3 6-1 on Sunday.

Thiem served superbly once again and broke twice in each set to end the unseeded Klizan's perfect record in finals, the Slovak having won all six of his previous deciders.

The world number eight saved the only two break points he faced and lost just 11 points on serve to claim the 11th title of his career, overcoming Klizan for the first time in four attempts.

Thiem took a firm grip on the decider after securing the first break to lead 4-3, that win his second of seven consecutive games as he surged to seal the first set and then lead 3-0 in the second.

Klizan lost his cool when he refused treatment on an ankle injury at a change of ends, throwing down his drink in disgust.

The left-hander failed to find a way back into the final, Thiem breaking again to lead 5-1 and putting Klizan out of his misery after the 65-ranked outsider saw his first two break-point opportunities come and go.