Mo Farah became embroiled in yet more controversy after impressively winning his first race since doping allegations against his coach came to light in Lausanne on Thursday night.
Farah kicked away from Ethiopia's Yomif Kejelcha in the final 100 metres of the 5,000m race and punched the air as he crossed the line in 13 minutes 11.77 seconds.
It was an imperious run against a stacked Diamond League field from an athlete who has seen his world turned upside down in the past five weeks by the doping storm surrounding his coach Alberto Salazar.
But after the race he was accused by Andy Vernon of telling his Great Britain team-mate to "**** off".
Vernon, who came home in 15th place, and Farah were embroiled in a high-profile row earlier this year, with Farah claiming his compatriot questioned his nationality at last summer's European Championships.
Vernon, who denied those accusations, said he approached Farah after the race in a bid to smooth things over only to be given short shrift.
"I went to shake his hand and he turned his back on me and told me to **** off. I wanted to bury the hatchet, I'm going up to Font Romeu (a training base in the Pyrenees) in a few days' time and I just wanted to end it," Vernon was quoted as saying by several national newspapers.
"It's in the past, I don't know why we can't just forget about it.
"To not even be a sportsman there and shake my hand I think is pretty disgraceful, to be honest.
"Like in the armed forces, you salute the rank not the person sometimes. I wanted to congratulate the performance. Whether we're friends or not, I can appreciate a good performance so I'd like to congratulate him, but I get that reaction."
Asked if there had been a clash with Vernon after the race, Farah said: "I don't know, not that I saw."
On the track, Farah, whose last race was 41 days ago, led with two laps to go, controlling the pace from the front, and was still in the lead at the bell.
Seventeen-year-old world leader Kejelcha moved past him with 300m to go, but the Briton's most potent weapon is his finishing speed and when he moved up a gear down the home straight his Ethiopian rival had no answer, coming home in 13mins 12.59secs.
This was no easy return for Farah in his first 5,000m outing of the year. He was back in at the deep end and, running in the distinctive black kit of the Nike Oregon Project, his elation at the line was plain to see.
Farah, who is gearing up for the defence of his 5,000m and 10,000m titles at next month's World Championships in Beijing, has been caught up in the doping allegations surrounding Salazar, who has denied claims made by BBC Panorama and US investigative website ProPublica that he violated several anti-doping rules.
The Briton, who has not been accused of any wrongdoing, has vehemently insisted he is "100 per cent clean", saying the allegations were "killing" him and his family, but is sticking by his under-fire coach.