Jack Draper had to battle back from 4-2 down in a deciding set tie-break to beat Jaume Munar in the first round of the Cincinnati Open.

British number one Draper won 7-5 3-6 7-6 (7-5) against the Spanish qualifier and will face Greek ninth seed Stefanos Tsitsipas in the next round.

The 22-year-old came through despite an injury concern late in the deciding set - calling for the physio when he was 6-5 up to receive treatment for an abdomen problem.

He looked to be struggling in the early stages of the tie-break but finished strongly to seal victory with the second of three match points.

Tsitsipas beat Germany's Jan-Lennard Struff 4-6 6-4 6-3, while world number one Jannik Sinner progressed with a 6-4 7-5 victory against American qualifier Alex Michelsen.

Top seed Sinner will face Australian Jordan Thompson in round two.

British duo Katie Boulter and Harriet Dart were both knocked out in the first round.

Boulter was beaten 6-2 0-6 5-7 by Poland's Magda Linette, while qualifier Dart was defeated 6-4 0-6 1-6 by Yulia Putintseva of Kazakhstan.

Five-time Grand Slam champion Iga Swiatek needed three sets to overcome qualifier Varvara Gracheva in the first round.

World number one Swiatek, who is also top seed, breezed through the opening set, before being taken to a tie-break in the second. She eventually booked her spot in the second round 6-0 6-7 (8-10) 6-2.

Players are preparing for the US Open - the final major of the season - which begins on 26 August in New York.