THOSE two magnificent free-kicks and that most clinical of penalties.

What a high John Guidetti was on when Celtic took Partick Thistle to the cleaners in the League Cup quarter-finals in late October.

That hat-trick in a 6-0 victory took his tally of goals to eight in six games. The Swede would score 10 in his first 12 appearances for the Parkhead side after joining on loan from Manchester City, but it has become tempting to reflect on that virtuoso performance against Maryhill's finest and wonder whether it offered an indication of difficulties to come.

Certainly, Guidetti is in a very different place ahead of his first visit to Partick's Firhill home on league duty tonight. For starters, he is unlikely to even make it into the starting 11.

Before the turn of the year, Celtic were eager to tie Guidetti down on a permanent contract. Talks have now stopped altogether. Maybe reacting to a speculative story linking him with Marseille with the verdict that "it is a beautiful city with an amazing stadium" created the impression that his heart did not quite belong to the east end of Glasgow.

Guidetti hasn't managed a goal since hitting the mark from the penalty spot in a 4-0 win over Hearts on November 30. He has lost his place in the team to Leigh Griffiths. Talking to his manager, Ronny Deila, you get the distinct impression, although the Norwegian would not say as much, that his star centre-forward, still just 22, allowed the adulation and the plaudits to take his eye off the ball.

"In the last three weeks, he has been working really hard in training and I know he will come again," said Deila. "Before that, the intensity wasn't where I wanted it, but I think he now understands what it is all about."

Perhaps it is placing too great an emphasis on body language, but Guidetti certainly had the look of someone who believed he was invincible that night he scored three against Thistle.

After bending a sensational free-kick into Scott Fox's top right-hand corner from 30 yards or so to make it 3-0, he jogged towards the Main Stand, gesturing to his team-mates to keep their distance from him before pointing to his chest, almost proclaiming himself the New King Of Parkhead. Talk about walking before you can run.

"The worst thing in life is to have things going well because it is so easy to use your energy on other things," said Deila. "You are not aware of why you are good.

"In the period we are in just now, things are going good as a team, but we still have to be very precise in everything we are doing, as if we had lost five games in a row.

"That's the mentality, that's professionalism. That is (the view) of those who win trophies.

"I think a lot has been going on in John's mind, but he now has the right focus.

"When everything is going well, people start to get individualistic.

"In Norway, for example, we have a lot of money, so, now, everyone is thinking about self-realisation. It's not about taking care of each other. It is about saying: 'I'm going to look perfect and I'm going to have the most perfect house, the best car, the best job'.

"When things go bad, everyone starts coming together and doing the easy and important things. That's what happens in football clubs, too.

"When things are going well, you have to understand why. It is because your team-mates are doing well and you are doing the right things.

"You are a big star at Celtic, but you have to understand why you are a big star.

"You have a thousand offers to do different things and you have to choose the right ones.

"That's what young players have to learn."

Deila insists he has not given up on keeping Guidetti at Celtic, with the club having agreed a transfer fee as part of the deal that brought him on loan from the Etihad Stadium, but it does not feel as though either side is pushing particularly hard with the likes of Ajax and Southampton rumoured to be waiting in the wings.

"We work on that all the time, but we don't want a player who doesn't want to be here, that's for sure," said Deila.

"If he wants it and comes back, we will start talking again. It is good for him that we don't talk about it just now.

"He doesn't want to talk about it and we don't want to talk about it."

Deila also puts part of Guidetti's loss of form down to the demands of playing so much midweek cup football in the early stages of the season. The Swede scored 20 goals in 23 games during a loan spell at Feyenoord in 2012, but he contracted a virus there that kept him out of action for the best part of a year and then spent further time on the sidelines after undergoing surgery on a knee problem.

"Everyone has to remember that he was out for two years," said Deila.

"He started scoring a lot of goals here, but didn't manage to play three matches a week because his fitness was not good enough.

"We have to work on his mental aspect and on being a 24-hour athlete."