UPDATE 2-Tennis-Kyrgios melts down again during Cincinnati loss

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 office 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 has 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.