The Hoops started their Champions League campaign on Tuesday as they travelled to Gibraltar to take on minnows Lincoln Red Imps.
They had envisioned a comfortable victory in what was Brendan Rodgers' first competitive game in charge.
Things did not go to plan though, as a goal from Lee Casciaro led the home side to an unlikely victory.
And McGarvey has blasted the current Celtic playing squad following the defeat, saying that only Griffiths and Tierney are good enough to play for the club.
“It says something when you are turning to Nadir Ciftci to get you out of trouble in Gibraltar,” he told the Daily Mail.
“In my opinion, only Leigh Griffiths and young Kieran Tierney are good enough to pull on a Celtic strip going forward.”
It now remains to be seen whether the defeat will convince Rodgers that further signings are necessary in the transfer window.
It is widely believed that this current squad is not good enough, especially after they failed to reach the group stages of the Champions League in the last two seasons under former manager Ronny Deila.
Tuesday’s defeat has only helped to strengthen that belief, as shown by McGarvey’s comments, and it will be interesting to see if Rodgers feels the same way in the coming weeks.