Both players were named on the bench at Craven Cottage and were taking part in a rondo drill with the rest of the substitutes, though tempers flared when Ceballos went in late on his teammate.
The initial challenge resulted in a furious exchange of words and a shove from the Spaniard, with the incident escalating after a second late and overly zealous tackle.
Ceballos got in Nketiah’s face, who stood his ground, and the pair started pushing and screaming at each other before a member of the coaching team pulled the striker away.
BT Sport’s punditry team played down the incident, with Rio Ferdinand claiming it happens all the time in training, and it appears the two players have already forgotten about it.
Ceballos uploaded a picture alongside a smiling Nketiah to his Instagram stories following the victory over Fulham, with the two appearing in great spirits.
Alongside the photo, the Spaniard wrote: ‘No problems here my brother.’
Manager Mikel Arteta was also asked about the incident at his post-match press conference but, taking a leaf out of Arsene Wenger’s book, claimed he was unaware of what happened: ‘I haven’t seen anything, sorry. I was inside.’
Asked if the clash was actually the kind of passion that a club needs, Manchester United legend Ferdinand said: ‘Yeah of course, this is part of it. I think at the end of the day sometimes it gets heated.
‘You’d see that probably once or twice a week at the training ground. It’s just we happen to be here, we’ve seen it. I’m sure Arteta won’t be too disappointed to see that.’
Peter Crouch added: ‘That’s good passion I think.’