RONNY DEILA believes rejuvenated Leigh Griffiths has become a '24-hour' footballer.

The former Hibs striker struggled for game time under the Celtic manager when he first took charge of the club in the summer with only a handful of appearances.

Griffiths' omission from the starting line-up - and at times even the matchday squad - led to reports that he was on the verge of a loan move back to Easter Road.

Deila had also stated earlier in the season that the 24-year-old needed to work harder to prove himself, but he now believes he has done just that.

Griffiths came off the bench in Sunday's 2-1 defeat at Dundee United to grab his team's goal before later hitting the post, and the Celtic manager has praised him for his change in attitude.

"He has become that 24-hour footballer," said Deila. "I think it's him being conscious. Everything is about being conscious of what you are doing all the time. You must always ask yourself 'What I'm doing just now, will it make me a better football player?'. If the answer is yes then do it more, if not then do it less.

"That's what we want to achieve here. A culture with reflection where you take on decisions that you do in life all the time, both on and off the pitch.

"You have to learn from your experiences. That's about knowledge. All the players here want to get the best out of themselves, but we must guide them.

"Leigh has made some very good decisions over the last two months. He looks much more sharper, he's scoring goals, he runs more and is quicker. He is becoming the player he can be."

One of the main credits to Griffiths' name has been his attitude in recent weeks.

That was typified last Thursday when the striker drove down to Sunderland to play - and score two goals - for Celtic's development squad in a 2-1 win over the Black Cats.

Deila said: "He got a choice. I didn't say 'you go and play'. I told him he could go if he wanted to. He then wanted to drive three hours to play, which is a very good attitude.

"He is taking responsibility for his body and he knows he needs to play games. When he does that it is very good.

"It's hard for me to say what happened before. I just see a lot of improvement in what I want to see improve.

"Leigh is happy with that and feels sharper. I'm happy with it, too. Now it's about working about other issues, it never stops.

"You can take steps, but it's still a long way to go to be the top striker he can be. We can work on the physical aspect, he can be stronger, but now he is leaner, quicker and is scoring goals. It's a good start."

Like Anthony Stokes, Deila has used Griffiths out wide in different situations with preferred striker John Guidetti at the apex of the attack.

It's a forward position which the Celtic manager acknowledges Griffiths would be best suited to, but he believes adding more strings to his bow will only help the Scotland international.

He said: "I am trying to get him to play in different roles as well, especially on the right coming in, but he needs to work more on his relationship with the other players.

"He is good when he gets on the ball and he has an unbelievable shot. And he gets chances.

"He has something to work on as regards linking up with others, but he can go behind the defence, he can get on the ball and he can hit the target with a shot so he is a top goalscorer. It is going the right way."