Nick Kyrgios continued his feud with umpire Fergus Murphy during his second round loss to Karen Khachanov at the Cincinnati Masters on Wednesday, loudly abusing the official before leaving the court to smash some rackets.
The Australian faces a heavy sanction from the ATP after clashing with on-court officials for the second time in as many weeks and with Murphy for the second time this month as his frustration mounted during his 6-7(3) 7-6(4) 6-2 loss.
Kyrgios confronted Murphy late in the second set and accused him of starting the shot clock too early. He was ultimately issued a point penalty at the end of the second set tiebreak after insulting the Irish umpire using an expletive.
The unseeded 24-year-old then left the court for what he deemed a bathroom break, despite protests from Murphy, and television pictures showed him smashing his rackets in a tunnel.
Kyrgios, who left the court without shaking Murphy's hand, clashed with the Irish official two weeks ago at the Washington Open, which he went on to win, and also had a run-in with another umpire over a towel last week in Montreal.
Murphy was also the subject of an expletive-ridden rant from Kyrgios at the Queen's Club Wimbledon warm-up tournament in June.
Russian eighth seed Khachanov kept his own cool throughout the histrionics and ended the match by winning three straight games to set up a meeting with France's Lucas Pouille for a place in the quarter-finals.
Unseeded German Jan-Lennard Struff earlier resisted a Stefanos Tsitsipas fightback and Serbian teenager Miomir Kecmanovic beat fifth-seed Alexander Zverev in two big upsets.
Struff, who has yet to win an ATP singles title in his decade-long career, was on top for most of the match against the 21-year old Greek.
He served for the match in the second set but Tsitsipas managed to stay alive by taking the set on a tiebreak.
However, the German refused to give up and sealed the 6-4 6-7(5) 7-6(6) victory to set up a third round meeting with ninth-seed Daniil Medvedev, who beat France's Benoit Paire 7-6(2) 6-1.
"I had a chance to serve it out at 6-4 5-4 but he broke back and that's the quality he has," Struff said.
"The quality I had today was coming back from that, the chance to win the match in two sets, then at 6-3 in the (third set) tie-break and then from 6-6.
"He was playing very well. I was telling myself 'I have to go for it, otherwise I won't win'.
"I've been working hard with my team on my fitness and it's all finally paying off and I'm playing with greater consistency."
Struff's compatriot Zverev was less consistent as he served a career-high 20 double faults in his 6-7(4) 6-2 6-4 defeat to the 19-year-old qualifier from Belgrade.
The second youngest player in the top 100, Kecmanovic's victory was his first against an opponent ranked in the top 10 and he is projected to advance into the top-50 next week.
Among the other surprises on Wednesday, world number five Kei Nishikori was beaten 7-6(2) 6-4 by Japanese qualifier Yoshihito Nishioka, while Canadian Denis Shapovalov also lost 6-4 6-4 to Lucas Pouille.
World number one Novak Djokovic and third seed Roger Federer advanced to the third round on Tuesday.