Celtic manager Ronny Deila claims they have a "fantastic atmosphere" on the training ground despite revealing full-back Emilio Izaguirre needed stitches after being on the receiving end of Nadir Ciftci's short temper.

Izaguirre suffered an ear injury after Ciftci lashed out following a challenge from the left-back. It is believed the former Dundee United player kicked out at the Honduran on the ground.

Despite not being present himself, Deila was open about the incident, which happened when press photographers and camera crews were at Lennoxtown ahead of Celtic's pre-match media conference for their League Cup quarter-final against Hearts.

The flashpoint came days after Kris Commons apologised for a dugout tantrum after being taken off during Celtic's 3-1 Europa League defeat by Molde in Norway.

Deila reacted in similar fashion to the latest internal dispute, claiming that training ground passion was necessary for a winning team.

"It happens all the time," he said. "We want intensity in training. It was a tackle and a reaction and he (Izaguirre) got hit in his ear. He had to go to get it stitched and he's fine for tomorrow.

"It was a reaction from another player to a tackle.

"I always say to my players I want 100 per cent. They are very good at that.

"We have a fantastic atmosphere in the training pitch. It's been very good lately. Sometimes it goes a little too hot and today there was an incident but I have talked with both players and everybody is ready for tomorrow."

Deila confirmed it was Ciftci who reacted and the identity of the aggressor came as little surprise.

The 23-year-old missed the first six games of the domestic season after being banned for biting Jim McAlister during a Dundee derby in May.

He received one red card and 11 yellows last season and escaped bans after being cited for violent conduct against Inverness defender Gary Warren and Celtic skipper Scott Brown, who accused him of kicking him in the head.

Ciftci was also banned the previous season for placing his hand on an assistant referee's throat during a League Cup tie at Inverness and was reduced to training with the youth team at previous club NAC Breda following several training-ground bust-ups.

Deila added: "I wasn't there. We sorted it inside. We talked with both of the players and we are finished with it and we move on with every focus we can have on tomorrow."

The intensity of Tuesday's training session was a fitting warm-up for one of Celtic's toughest domestic tests of the season at Tynecastle.

Celtic comfortably knocked Hearts out of both cups last term but Robbie Neilson's side were focused on promotion and are now more eager for cup success.

They also showed their improvement by holding Celtic to a goalless draw at Parkhead last month.

Deila said: "We should have won that game but it's going to be a different game when we play away.

"They are a good team and we have to be up for the fight first of all. And we need to get the quality on the pitch so we can score some goals and get the win.

"They are coming up to be a Premiership team and they are number three in the league so they are one of the best teams in the country right now. They have improved but they were good last year as well so it's no surprise to me that they are where they are just now. They are a big club.

"They are a physical team but we handled that well when we played at Celtic Park. We should have scored goals. That was missing but we beat them twice last year so we have confidence going into this game."