Celtic manager Ronny Deila hailed the contribution of striker Leigh Griffiths after he came off the bench to claim a quick-fire hat-trick in a 4-1 win over Kilmarnock.

The Scotland striker took just 24 minutes to complete his treble after replacing the ineffectual James Forrest on the hour mark with the scores locked at 1-1 following Daryl Westlake's opener for Killie and Kris Commons' equaliser for Celtic.

Griffiths headed the home side in front in the 65th minute before thumping a vicious 25 yard strike past Killie 'keeper Craig Samson with ten minutes remaining.

The former Hibernian striker then beat the off-side trap to complete his hat-trick with an angled shot five minutes later.

His manager was quick to praise the striker's performance, but insisted there was still more the former Wolves forward could do to improve.

"It was fabulous from Leigh. You can't get better than that; three goals and his contribution was excellent," Deila said.

"He has improved a lot in my time here. He is training well and as a 24-hour athlete he is getting better and better.

"It's much better from him, but it's still just a start. He has to continue to work on small things to get better and then we will get even more goals and better performances out of him."

The goals take Griffiths' tally to 15 for a season where he has struggled to hold down a starting position in the Celtic team.

And Deila says he is happy for the striker to prove him wrong and claim a permanent place in his starting 11.

"It looks like he is trying to prove me wrong and that's the way to do it. That's what I expect from the other substitutes as well," the Norwegian manager said.

"You can be angry, but the only way to get back into the team is to really prove you deserve to play, like Leigh did today.

"Also we have to think as a team. Sometimes you are on the bench if you started at the weekend and then you can come on and make a big contribution. That's very important for a team."

The win extends Celtic's lead at the top of the Scottish Premiership to eight points with six matches remaining.

The Hoops are now just four wins away from claiming their fourth championship in a row and could clinch it at the home of their closest rivals Aberdeen if both teams win their matches before their meeting on May 10.

But Deila is keen to wrap the title up as quickly as possible.

"Hopefully we will win it before that. It's possible if they lose a game and we win then we can do it," the Celtic boss said.

"We want it finished as soon as possible. Today was a very important win and we are into a very important week now.

"If we can get into the last five games with eight points at least ahead then we have a very, very good chance."