Brendan Rodgers felt Dedryck Boyata had only himself to blame after being red-carded in the 1-0 Betfred Cup win over St Johnstone at McDiarmid Park.
Leigh Griffiths scored the only goal late on as Celtic got a hard-earned win, though Boyata was ordered off in the final minute, earning his marching orders for dissent against referee John Beaton.
The dismissal means that Boyata will miss the semi-final meeting against Hearts next month and his manager was short on sympathy with the Belgian.
“It is a stupid red card,” said Rodgers. “He has got enough opportunities to not get sent off. It was a very emotional game towards the end.
“Dedryck feels as if he should have got a free-kick and didn’t get it. “In fairness to John, he gives him a chance not to get the red card. It’s not what we would want.”
One player that did get Rodgers’ approval was match-winner Griffiths, after the striker netted his third goal in six days for the club.
The Scotland international signed a new four-year deal to remain at Parkhead earlier this month and his manager is delighted with what Griffiths is doing currently.
“Leigh could have had a hat-trick, but what is important is that he is smelling the goals again,” said the Celtic manager.
“He is making the right moves. He had a couple of great opportunities getting into good positions and credit to their keeper as he made a couple of great blocks.
“Leigh is always going to be alive in the box for chances coming and it was a great finish.”
Celtic are 1.85 to retain the Betfred Cup, with semi-final opponents Hearts 8.00 to lift the trophy.