Reece James appeared to applaud Mason Mount during Chelsea's dramatic 4-3 win over Manchester United on Thursday.
Mount made his first return to Stamford Bridge since leaving his boyhood club to join United last summer in a £60million move.
His introduction in the second-half was greeted with jeers and boos, with some Blues supporters appearing to believe Mount was something of a 'traitor'.
However, Reece James looked to have clapped for his former team-mate as he made his way onto the pitch.
The Blues captain was sat behind the bench as he continues his recovery from a long layoff after suffering a hamstring injury.
Mason Mount made his first return to Stamford Bridge since leaving Chelsea to join United
Reece James clapped for his former team-mates as he came on to a chorus of boos
James and Mount spent years together in the youth ranks before both breaking into the first team in 2019
James' action may come as no surprise given the pair are good friends having come through the Chelsea youth ranks together before both breaking into the first team in the 2019-20 season.
Enzo Fernandez and Mount clashed later in the match, with the Argentine midfielder sending an X-rated tirade the latter's way.
Meanwhile, TNT Sports cameras caught the moment when a Chelsea fan lifted up a 2021-22 edition of their home shirt which read 'JUDAS 19'.
Though Mount wears the No 7 for United, during his Chelsea days he wore the No 19 - making it a clear reference by the home supporters.
It was a night to forget for Mount, who spent four full seasons at Chelsea, as he watched his side capitulate deep into added time at Stamford Bridge.
Conor Gallagher had given Chelsea a 2-0 lead, before Alejandro Garnacho and Bruno Fernandes struck back before the break, the Argentine forward heading a third for United after the interval as the Blues looked set for a bruising defeat.
But with 99 minutes on the clock, Noni Madueke won a penalty which was converted by Palmer, who then somehow made it 4-3 82 seconds later with a 101st-minute winner to spark jubilation for the hosts at the Bridge.