LEIGH GRIFFITHS is nothing if not hard on himself and also his team.

The Celtic striker is still smarting at missing a penalty against FC Stjarnan last week in an overall performance he deemed not good enough, despite his side enjoying a 2-0 lead over the Iceland champions at halfway stage of this qualifier.

And despite the fact he was not totally to blame for not getting his team a third given that Stefan Johansen did his best to put him off.

Griffiths did not think he or Celtic as a whole did themselves justice in that first game. If they had, according to him, then this tie would be done and dusted.

And he may well be right.

However, it still should be straightforward enough on Wednesday night. Stjarnan's form, which could at best be described as mediocre, suggests we might have seen the best of them even if the No9 warned against complacency.

Griffiths scored a hat-trick in Celtic's 4-1 win over Eibar in a friendly match arranged to celebrated the club's 75th anniversary and while that was just a friendly and not a Champions League second leg qualifier, the goalscorer wants to see a repeat of that performance in the Basque country in Iceland tomorrow night.

Speaking to the official Celtic website, Griffiths said: "It (the game against Eibar) was a good test for us going into Wednesday night.

"We got the win last Wednesday but I don’t think we played as well as we could have and we showed against Eibar what we’re all about.

“I got 90 minutes so I’m feeling sharp but it’s a different kettle of fish on Wednesday night with the Champions League.

"Whatever team the manager goes with we need to put in the performance, get the win and make sure we get into the next round.”

Griffiths can give off the impression of not taking anything too seriously, especially himself, but this guy is a professional and hates not reaching what he perceives to be his highest standard.

He got his hat-trick in Spain, but only after giving himself a talking to at the interval having gone in at the break feeling disappointed with his own performance.

Griffith said: "I was disappointed with myself in the first-half. I slipped in Darnell Fisher when I should have had a shot.

"In the second half I managed to put a penalty away after missing one on Wednesday night and got another two so I’m happy."

And he was especially happy to score his third after latching on to a long pass from Virgil van Dijk.

Griffiths said: "I knew we were 3-1 up near the end and I just wanted to stretch the game.

“I didn’t know Virgil was going to play it but when he did there was only one thing on my mind and that was to try and go for goal.

“Nine times out of 10 any other player would try to take it into the corner but I wanted that third goal.”