Infuriated by his apparent disregard for his own development, Guardiola is reported to have sent Mendy back out the way he came when he finally did emerge last Sunday.
City have scored 21 goals in their seven Premier League games this season - a better strike rate than the record 106 they got last season.
Manchester City have officially confirmed their starting side and substitutes to host Brighton at the Etihad Stadium in a Premier League meeting.
Sources have told ESPN FC that it is not the first time the 24-year-old has been reprimanded for being late for training while he has recently given a 12-month driving ban.
Mendy had spent the previous night in London watching Anthony Joshua's world heavyweight boxing title fight against Alexander Povetkin.
It looks unlikely either Delph or Mendy will feature in Germany, meaning Zinchenko - who filled the role on occasion last season - is tipped to do so again. We spoke about him playing 55, 60 mins.
The two sides would meet once more in the 2013/14 season in the German Cup final, with Arjen Robben and Thomas Muller scoring to seal a 2-0 win for Bayern and the double for Guardiola in his debut season.
"He arrived late, that happens sometimes, in the last period a lot have arrived late because of the traffic".
"I expect him back when he's fit". Every day he's having treatment.
"Now he's injured, he's not a problem with physical condition, he's quick".
"He's injured and when he's ok he's coming back and when he decides to play he's going to play".
"Sergio is struggling a bit with some problems in his foot", Guardiola said.
Brighton had a late penalty appeal after Fernandinho appeared to handle but their goalkeeper, Mat Ryan, also had to make three impressive saves, from Sterling and Fernandinho in the first half and David Silva in the second.
"He needs to go step by step, don't read too much, watch too much, train hard and his career will speak for himself", Guardiola said.