2017 runner-up Damir Dzumhur withdraws from Winston-Salem Open

Bosnian tennis ace Damir Dzumhur pulled out of the Winston-Salem Open just before his opening match due to a back injury.

The Bosnian, who debuted on the hard-courts of Winston-Salem in 2014, was expected to make his fourth main draw appearance at the tournament this year.

Woeld No. 24 Dzumhur, who was seeded at No. 5 in the Winston-Salem draw, had a first round bye and was set to meet this year's Australian Open quarter-finalist Tennys Sandgren in his opening match on Tuesday.

The match between Dzumhur and Sandgren never took place as the world No. 24 was replaced by lucky loser Dominic Koepfer.

Dzumhur failed to make it past the Winston-Salem qualifying event in 2015 and lost in the first round at the tournament in 2014 and 2016 before he made it all the way to the final stage last year.

Back then, the world No. 24 won five matches in a row but just couldn't clinch another win and stun Spain's Roberto Bahrista Agut in the final.

The Bosnian will now have a couple of days to take care of his injury and try to get as fit as possible for the US Open.

Dzumhur kicked off his summer hard-court season with a semi-final showing at the ATP 250 event in Los Cabos but then lost in the first round at the Masters 1000 events in Toronto and Cincinnati.

The Bosnian is set to play in the US Open main draw for the fifth time in his career.

The 24-year-old's career-best result at Flushing Meadows came last year when he reached the third round before he lost to Russian rising star Andrey Rublev.