Celtic manager Ronny Deila has slammed Dundee United's Ryan McGowan for his "stupid" challenge on Liam Henderson which he believes could have ended the youngster's playing career.

The Australia international was shown a red card late on in the Hoops' 4-0 Scottish Cup quarter-final victory, just two minutes after Anthony Stokes had himself been dismissed in the fiery affair.

This fixture has now seen six red cards in its last three meetings, with all those games coming in the past 11 days, and Deila was quick to condemn McGowan's challenge.

"It was a red card, a stupid tackle on the sidelines," he is quoted as saying by FourFourTwo. "We need to get these things out of football.

"It was a youngster trying a little trick in the corner. You could have stayed there and kept him out wide instead of going in with both feet. He could have injured him for life. At 4-0 it must have been frustration."

McGowan later took to Twitter to apologise for the heavy tackle, while Dundee assistant manager Simon Donnelly claimed that he felt it was not worthy of a straight red card.