Mo Farah and his 5,000 and 10,000m rival Andy Vernon were caught in a heated Twitter spat.
In the extraordinary hour-long exchange, Farah described his former British team-mate as an "embarrassment", after Vernon criticised the lack of high-level competition the 31-year-old will face at the Sainsbury's Indoor Grand Prix on Saturday.
"Another stellar field against Mo Farah on home turf this weekend at Birmingham. #joke," wrote Vernon.
The double Olympic champion replied: "Shame you didn't make the line up....again #ComeBackWhenYouWinSomethingDecent"
Vernon, who earned his best career result to date when he was second to Farah in the European 10,000m last summer, had a biting comeback of his own.
"Lol Mo Farah I think even you can work out that I can make the cut to the Indoor Grand Prix. Let's hope no one loses their shoe..."
@AndyVernonGB that's why they didn't put you in the race mate.. Cos you're an embarrassment!! Taylor swift can probably run faster than you!
— Mo Farah (@Mo_Farah) February 17, 2015
Farah responded: "I wish you did make the cut mate so I can leave you in my dust like ALWAYS!! hahahaha #hatersgonnahate" The exchange continued with Vernon replying: "1) stop quoting Taylor Swift. 2) I don't hate you Mo. I would just rather watch a race than the Mo Show. #playersgonnaplay."
Refusing to let it go, Farah responded with a stinging rebuke tweeting: "that's why they didn't put you in the race mate.. Cos you're an embarrassment!! Taylor Swift can probably run faster than you!"
Reflecting on the argument, that left their respective Twitter followers less than impressed, Vernon later tweeted: "Don't know why this got so blown up. It's no secret that Mo gets weaker fields put together for home races. Ian Stewart would tell you himself."
In a subsequent interview with Telegraph Sport Vernon described Farah as "arrogant" for calling him an "embarrassment."
— Andy Vernon (@AndyVernonGB) February 17, 2015
"It was a worse retaliation than I thought I might get," he said. "I thought he would just ignore it because I didn't say anything malicious or offensive. I thought he would just take it as a joke or give me some banter back. I put in a jab but he put in a haymaker below the belt and it sparked off from there.
"I don't really care what he says about me but it is the way that he said it," he added. "If he thinks I'm an embarrassment then what does he think about everyone else? That's the bit that I found arrogant."
Farah will be the star attraction at this weekend's meeting at the NIA Barclaycard Arena in Birmingham which also features European 100m champion James Dasaolu and European and Commonwealth 200m silver medallist Jodie Williams.
The pair will not face disciplinary action as they have not broken any social media rules.