A probe was under way today into angry scenes at Wimbledon which led to one of the players apparently spitting at the crowd before storming off court.
Romanian Victor Hanesco was contesting the fifth and final set of his third-round match against German Daniel Brands yesterday on Court 18 when he threw in the towel.
Four people were arrested at the court - but the All England Club (AEC) said the arrests and the spitting incident were not linked.
A clearly rattled Hanesco complained to the umpire before the start of the set, the commentator saying he was not sure if Hanesco was unhappy with the crowd or something somebody had said to him.
He played on, but at the start of the third game - at 2-0 down - he walked towards the corner of the court and appeared to spit at the crowd before looking intently at the spectators and muttering angrily under his breath. He received a warning from the umpire.
He then continued the game but appeared to deliberately double fault the last two points, prompting jeering from the crowd, before conceding the match.
Police confirmed four people were arrested in Court 18 - coincidentally the scene of the longest tennis match in history which had been played out earlier in the week.
An AEC spokesman said: "The initial thought was that the four people arrested were part of the same spitting incident. But the thinking now is that possibly they weren't. That was just a random coincidence.
"Therefore this alleged spitting incident is directed at a different person or people who we don't know."
A Scotland Yard spokeswoman said four men were being questioned under the Public Order Act.
She added: "The arrests are for the police, the spitting incident is for the All England Club.
"Police were called to Court 18 following a disturbance.
"Four youths were arrested. They have all been taken to a south London station under Section 5 of the Public Order Act."
Championships' referee Andrew Jarrett said in a statement: "Victor Hanescu retired from the match due to a leg injury."
Hanescu was struggling with an injury during the latter part of the match and received on-court treatment.
He could face severe punishment. A standard offence of unsportsmanlike conduct carries a maximum fine of £6,600.
Under Grand slam rules, any act deemed to be "flagrant and particularly injurious to the success of a tournament" can be judged as a "major offence of aggravated behaviour".
The AEC spokesman added: "The umpire has seen it (the spitting incident), if that's what it was.
"The umpire issued a code violation for unsportsmanlike conduct that covers things like spitting and swearing. His report will obviously be considered along with any other witnesses that we have from our side and then the referee will obviously look at those and any other footage he's got available to him with his colleagues, and at some stage will make a decision on what should or should not happen."
A spokesman for the Association of Tennis Professionals, who run the men's game, said there would be no comment from the organisation before Grand Slam supervisors and referees meet in the morning, as they do each day, to discuss disciplinary matters.