It's certainly not the first time there have been problems between the Coach and the Argentine, but with a trip to Catania on Sunday and fourth place at stake, the timing of this latest incident is terrible.
"He forgot the time of the training session, so this morning he turned up at 12 instead of 11 and did not train," revealed Reja in a Press conference.
"The schedule is pinned up outside the locker room for all to see, but I haven't decided how I'll deal with him.
"Whoever steps on to the pitch will give 100 per cent. I want to see character and temperament.
"We really need those elements in the fiery atmosphere of Catania. They have excellent players, but so have we and it's what happens on the field that decides the result."