Murray said Del Potro's comments about his mum were unacceptable
Andy Murray was involved in a minor bust-up with Juan Martin Del Potro during their first-round clash in Rome.
The Scot won the Masters contest when Del Potro retired in the third set but after the match Murray accused the Argentine of insulting his mother Judy.
"I don't think it was really that cool," said the British number one, who described his mother as "one of the nicest ladies you are going to meet".
Murray won through 5-7 6-4 1-0, his opponent retiring with an injury.
The Swiss beat Marat Safin 6-7 (5-7) 6-2 6-1.
According to BBC Radio 5 Live tennis correspondent Jonathan Overend, the problems between Murray and Del Potro started when the former accused the latter of smacking a drive volley straight at his head without apologising.
Then, during one verbal exchange when they were changing ends, the sledging turned personal when Del Potro made a comment about Murray's mother, who was watching courtside.
The 19-year-old South American was told to watch his mouth by Murray but the umpire, who warned the Scot for an audible obscenity earlier in the match, took no action.
Murray says it is only the second time in his career that he has had a problem with an opponent and said it inspired him to play his best tennis towards the end of a scrappy match.
The match had failed to start on time because of the weather and the rain intervened again, forcing the players off after only two games.
When the action restarted, Murray struggled in the first set and dropped serve in the 12th game to go 1-0 down.
But the 20-year-old, seeded 16th, recovered well, mixing his play brilliantly to take the initiative.
Del Porto then developed a problem with his back and was in a lot of pain as he received treatment at the start of the third set.
It was not long before the ATP trainer advised the teenage qualifier to call a halt to the contest.