Ronny Deila has been put under further pressure as Celtic boss after they were beaten by Rangers.
Celtic were beaten on penalties by their bitter rivals Rangers yesterday, and supporters of the Bhoys have reacted badly to the defeat.
The Bhoys went into the match as favourites to win, but they were well matched by Rangers, and Deila has received the brunt of the criticism.
Tierney, who was one of the few Celtic players to come out of the match with any credit, admits that he can totally sympathise with the emotions of the supporters of the club, but he is adamant that Deila remains the right man for the job.
"All of the players are behind the manager, 100 per cent all the way,” he said. “The players didn’t perform in the game. He has shown faith in all of us in that team and we back him.
“I can understand the anger of the Celtic fans because I am one myself. Obviously, we went out there and didn’t perform to our best, so we are all devastated.”
In the match, Celtic had to come from behind twice to even take the game to penalties, and there did not look like a division separated the two sides.
Mark Warburton’s Rangers side were highly impressive, and Celtic could not feel too aggrieved about their cup exit.
The defeat has plunged Deila’s future at Parkhead into further doubt, with his current contract due to expire in the summer.