Novak Djokovic has absolutely unloaded on a chair umpire at the Italian Open after receiving a time violation warning while serving.
The 12-time grand slam champion will face Juan Martin del Potro or Kei Nishikori in the last eight after beating Spaniard Roberto Bautista Agut 6-4 6-4 at the Foro Italico.
There were more encouraging signs from Djokovic ahead of the French Open as the second seed stayed in the hunt for only his second title of the year.
And there was fire in his belly, as he swore at the chair umpire after being broken in the second set, having been given a time violation.
"How can you give me a f***ing warning?" Djokovic fumed at the umpire at the change of ends.
"He's taking too much time," he said in reference to a ballboy.
"Recognise the situation for god's sake."
The time violation rule has been the source of much frustration in recent times.
Rafael Nadal and Australia's Daria Gavrilova were both left exasperated when hit with time violation warnings at the Australian Open in January:
Djokovic put the blame on a ball boy before channelling his frustration to secure a win that was sealed with a sublime forehand winner.
Djokovic has endured a disappointing year and recently parted company with his long-time coaching staff, but the Serbian appeared to have rediscovered some drive and broke three times to advance under blue skies in Rome.
Bautista Agut claimed his first win over Djokovic at the sixth attempt in the Shanghai Masters last October, but there was to be no repeat in the Eternal City.
Elsewhere Rafael Nadal picked up his 17th-straight victory by beating Jack Sock, while Stan Wawrinka crashed out at the hands of John Isner.