The Clydesdale Bank Premier League champions were trailing to a Simon Lappin strike when manager Gordon Strachan replaced the club's top scorer with Georgios Samaras on the hour mark.

The boos that greeted the substitution summed up the frustration of the home support and the Australian international, who has scored 26 times this season, showed his own feelings as he threw his tracksuit top away in anger before kicking out at a dug-out seat.

Strachan revealed that the 24-year-old former Motherwell striker had apologised after the game and McGarvey insists that should be the end of the matter.

McGarvey, who scored the winner for Celtic in the 1985 Scottish Cup final said he understood why McDonald had exploded.

He told PA Sport: "Scott has had a brilliant first season as a Celtic player.

"But he's having a poor time at the moment and he was just frustrated with himself.

"Strachan has to live or die by his decisions and he is not the first Celtic manager who has had to deal with something like that, it happened when I was playing and long before that.

"Three things got to McDonald. His own poor form, the lack of clear-cut chances being made for him and the fact that the defence cannot keep a clean sheet which puts him under more pressure.

"That all came to a head in the Motherwell game. There's too much being asked of too few at Celtic just now with too much pressure on McDonald and on Aiden McGeady.

"There is not a lot of creativity in the team at the moment.

"I had guys like Murdo MacLeod, Tommy Burns, Paul McStay and Davie Provan who would create opportunities for the strikers but also chip in with a fair amount of goals themselves.

"It's been up to McDonald to score most of the goals this season. Other players are not contributing their fair share.

"He doesn't get a hand from his midfield players like Scott Brown, Paul Hartley and Massimo Donati.

"But Saturday is not a big problem. He has apologised and everyone can move on now."

Strachan admitted that the defeat to the Steelmen - who played most of the second half with 10 men after Bob Malcolm was red carded for a lunge at Donati - meant that it had become "near impossible" for his side to retain their title.

However, McGarvey does not believe the championship flag is heading to Ibrox - just yet.

"It's still not over yet but it's going to be very, very difficult," he added.

"If it was a great Rangers team they were up against then I would say the title was lost but it's not.

"Rangers look as if they could crumble at any point, some of their players look tired, there will be suspensions and injuries and they have a lot of games to play.

"But will Celtic be good enough to take advantage?"