Poznan challenger

International Tennis Federation: India’s top-ranked singles player Sumit Nagal has lashed out at the refereeing standard in tennis after a controversial umpiring call during his opening-round match at the Poznan Challenger.

Taking to social media on Tuesday, Nagal highlighted what he called a "massive flaw in our sport," after the chair umpire reportedly made error in a single point and refused to inspect a ball mark on the clay court.

"I was playing a point, where I ran towards the ball, which was clearly out. There was a linesman and a chair umpire refereeing the match. The call never came from either of them. So I raised my hand immediately... but the umpire claims she didn’t see it, which can happen, but then she refused to come down and even check the mark," Nagal wrote.