LEIGH Griffiths last night admitted he still fears being sacked by Celtic due to his troubled past - despite scoring 38 goals this season and signing a contract extension until 2021.

Griffiths, a lifelong Hibs supporter, was issued with a final warning by the Parkhead club in 2014 after being filmed signing an offensive song about Rudi Skacel, the former Hearts player, in a pub before an Edinburgh derby at Tynecastle.

The striker has done superbly since that notorious incident - he scored 20 times last season as Ronny Deila’s team won a Ladbrokes Premiership and League Cup double.

Read more: Stubbs can be new Celtic manager - but must prove Hibs mettle first

This term his goals have helped take Celtic to the brink of a fifth straight Scottish title – they could wrap the league on Saturday if they beat Hearts in Gorgie and Aberdeen draw or lose to Motherwell at Pittodrie - and earned him a lucrative new five year deal.

However, Griffiths, speaking as he was announced as one of the nominees for the PFA Scotland Player of the Year award, has revealed the prospect of being offloaded as the result of another off-field transgression still worries him.

The Herald:

“I am still on my final warning,” he said. “Celtic might give me so leeway now and again, but I am pretty sure if there was a similar incident to Tynecastle then I would be shown the exit door.

“The warning came from the whole club. The letter got tossed in the bin after we won the league. But I can still tell you what happened in that meeting. I remember it like it was yesterday.

“Of course, that final warning was a huge scare. You don’t get the chance to play for Celtic that often and you have to make the most of an opportunity like that. I knew I had to knuckle down and get on with it. I couldn’t afford to make any more mistakes. At that moment I realised I had to grow up.

Read more: Leigh Griffiths describes claims the Celtic players aren't fit enough under Ronny Deila as "b******s"

“Let’s be clear, it was a final warning for me. What I did wasn’t acceptable and that was spelled out to me. But I knew it myself. I am a professional footballer first and foremost and you can’t be doing things like that. I have learned from it, I keep my head down these days.

"I think I have learned from my mistakes. For the last 18 months I’ve been on the back pages rather than the front and that’s the way I hope it continues. I haven’t been in any trouble and that’s the way it has to continue.

The Herald:

“I have concentrated on my football and I am reaping the rewards of that. I am scoring goals. That does help a wee bit, especially when we have almost got the league title wrapped up and I have made a good contribution to it.”

The Scotland internationalist, though, acknowledged he will have to work hard to impress Deila’s replacement when he comes in during the summer despite his prolific strike rate during the 2015/16 campaign.

"You have got to try to impress," he said. "My goal record speaks for itself, but unless you keep catching the manager’s eye you won’t be there.

“To be nominated now for this PFA Scotland Player of the Year award for having such a good season is great. But I can’t rest on what I have done this season. I want to keep pushing on and striving to keep breaking my own records. If you don’t you will not be in the team.”

Read more: Leigh Griffiths vows to give mentor Ronny Deila the perfect send-off - by firing Celtic to the Premiership title

Griffiths, a £1 million signing from Wolves at the start of 2014, scored four goals for Celtic in Europe this season. He netted in a Champions League qualifier against Stjarnan, bagged a double in the first leg of the play-off against Malmo and struck in a Europa League group game against Fenerbahce.

But the 25-year-old would like to ensure Celtic qualify for the group stages of the Champions League for the first time in three years next season and then star in Europe’s premier club competition.

“We have a fresh start next season and hopefully we will get there,” he said. “I think I proved against Malmo I can score goals in Europe. But the only way I can silence critics is by trying to do it on the big stage. We were close against Malmo, but hopefully we can go one step further next season."

Meanwhile, Griffiths has confessed that he would love Celtic to wrap up the Premiership with a victory over Hearts at Tynecastle on Saturday.

“It would be nice,” he said. “I do love playing there. It’s always a good atmosphere. It’s a hostile atmosphere and these are the games that you want to play in. But if it’s not this week then next Sunday in front of our own fans against Aberdeen would be great too.”