Reilly Opelka faces potential discipline for his post-match comments about a chair umpire he called the “worst ump on tour.”

Reilly Opelka called for chair umpire Greg Allensworth to be suspended by the ATP after Opelka received a code violation at the Dallas Open for confronting a spectator in the stands who he claimed was deliberately coughing to interrupt his serve.

Opelka criticized the umpire after he was penalized for twice swearing at a spectator, describing him as 'amateur hour' and 'bush league.'

Reilly Opelka launched into stinging criticism of chair umpire Greg Allensworth for penalising him following a confrontation with an "idiot" heckling fan.

Tommy Paul is through to his second semi-final of the season in Dallas. The Australian Open quarter-finalist faced fellow American Reilly Opelka in the quarter-final and scored a 7-6, 6-2 win in an hour and a half.

The American battled against Cameron Norrie in the second round and prevailed 4-6, 7-6, 6-4 in two and a half hours. Opelka dropped the opener and trailed 5-4 in the tie break of the second set. He kept composure and grabbed the final three points to force a decider.

Reilly Opelka's win over Cameron Norrie at the Dallas Open ended in controversial fashion and the American didn't hold back in his criticism of chair umpire Greg Allensworth after the match.

Reilly Opelka’s win over Cameron Norrie at the Dallas Open ended in controversial fashion and the American didn’t hold back in his criticism of chair umpire Greg Allensworth after the match. After coming from a set down to take the last-16 encounter to a decider,