Celtic manager Ronny Deila has admitted that he was disappointed with his side's first-half performance before they went on to beat Dundee United 3-0 at Tannadice Park.

The leaders survived a sluggish opening 45 minutes as Leigh Griffiths edged them closer to the title with a hat-trick which included a controversial penalty, and Deila was quick to pay tribute to the forward.

"I didn't have a good feeling about first half as we played really poor. Leigh Griffiths delivered. We have started to get to know one another and he knows what I expect and I know what he can contribute at the top level," the Norwegian told Sky Sports News.

"United have some good young players and they are tough to play against. I haven't seen the penalty incident; but if that decision was wrong I don't think it made any difference."

Celtic will clinch the title if they win against Dundee on Friday and Aberdeen fail to beat Dundee United on Saturday.