Deila has been in charge at Parkhead since the summer of 2014, but the pressure is beginning to mount, with the dissenting voices against his leadership increasing in volume.
And Brazil says that Deila should never have got the job at Celtic in the first place, as he wasn’t high profile enough for a club of that stature.
He said: "Ronny Deila, with the greatest respect to him, don't know where he came from, don't know how he got the job. But, in my opinion, he shouldn't be in the job."
Deila has delivered domestic success to Celtic in his time in charge, doing the double in his first season at the helm.
The Bhoys are well on course to defend their Scottish Premiership title this time around, but doing well in domestic competition is no longer enough for any manager of Celtic.
The Hoops’ supporters demand that their side perform well in Europe, but Deila has failed to deliver success in either the Champions League or the Europa League during his time in charge.
Celtic have gone out of the Championship League at the qualification stages for the last two seasons, and they also look to set exit the Europa League in the group stage this term.