Celtic's Norwegian manager Ronny Deila accused his team of lacking professionalism after two of them argued over who should take a crucial penalty in the Champions League second qualifying round tie against Stjarnan of Iceland.

The former European champions won 2-0 but Leigh Griffiths missed the late spot-kick that would have ensured a much more comfortable margin for the second leg in Reykjavik after Stefan Johansen and Griffiths argued over who should take it.

“It is Leigh Griffiths who takes the penalties, it should be very clear,” Deila told reporters. “There is nothing professional about it. We shouldn’t fight about who takes a penalty.

“Of course it impacts on the taker, it gives extra pressure to him. The longer you have to wait, the more chance you have to miss it.

“3-0 is a totally different result to 2-0, so it’s disappointing.”