Former Celtic striker John Hartson says he has "serious concerns" over Ronny Deila's position

In the 90 second clip, Hartson said he has concerns over the team’s “inability to keep clean sheets” and said the defenders have failed to take responsibility as a unit.

He also mentioned previous European clashes, where the team has failed to hold on to a lead on several occasions.

I'm concerned about my old club @celticfc and Ronny Deila's position. Big decisions have to be made quickly. #Celtic https://t.co/e6ZVb16bMN

— John Hartson (@JohnHartson10) February 4, 2016

In the online clip, Hartson said: “There are serious concerns about Ronny Deila’s position and whether or not he can get through big games and hold on to tight situations.

 “This has not just gone on in the last two or three games, this has been going on now for two and a half years.”

He added: “Basically there’s big decisions to be made and made quickly.”

Celtic cannot defend any decent ball that comes into their box.. It's cost them time and time again.. It's called defensive responsibily.

— John Hartson (@JohnHartson10) February 3, 2016

Ronny Deila’s position as manager has come under increasing scrutiny following Celtic’s 2-1 defeat to Aberdeen at Pittodrie.

The Evening Times has previously reported how Ryan Giggs has been linked to take over at the club.