ABERDEEN goalkeeper Joe Lewis says that defenders are making a meal of challenges from his teammate Sam Cosgrove as they know he is a 'marked man'.

The striker was given a straight red card in Aberdeen's 2-1 defeat to Celtic on Saturday for a tackle on Kristoffer Ajer, and while Lewis didn't accuse Ajer of feigning injury, he does believe that opponents are targetting Cosgrove due to the forward's reputation.

Lewis says that there is no malice in Cosgrove at all, and that his challenge was harshly punished by official Euan Anderson on Saturday.

"Sam doesn't have a bad bone in his body, on and off the pitch," Lewis said.

"I can't think of a terrible tackle he's put in, or an elbow in someone's face, or when he's left one on someone.

"It's difficult to understand why he has a reputation - if he has one. I haven't seen anything like that in training or games but we had a similar situation with Jayden Stockley. He was a marked man when he was here. Everything he did seemed to lead to a booking. Hopefully that's not the case with Sam.

"Refs don't have an easy job and need all the help they can get from their assistants and the fourth official.

"It's disappointing that tackles like that are now straight red cards. Nobody wants to see the game go that way.

"We don't want to see players injured and lunges off the ground with studs up should be reds as you endanger an opponent. But it's a shame that the game seems to be going that way.

"Players and defenders know that if you are tackled and make a meal of it, you maybe can entice the ref into giving a red.

"I'm not saying that's what Ajer did, but that is the danger of giving straight reds for what used to be good tackles, but are now not."

Lewis didn't have the best view of the red card incident, but his initial gut feeling was that his teammate had won the ball cleanly from Ajer.

And he has urged Aberdeen to appeal the decision if they can find video evidence to support that claim.

"I was 100 yards away from it so it's difficult to comment but he certainly won the ball," he said.

"I don't know how much contact there was and Sam is definitely going in at pace. But I felt Ajer took a loose touch and doesn't see Sam pressing him.

"It looked to me like Sam slid and won the ball, and it looked like a harsh red card, but the referee is closer.

"I don't know what contact there was on Ajer, so it's difficult to know whether he's made the most of it, or was genuinely caught.

"The club will take a look at it and see if it's worth appealing."