Neil Lennon has told Leigh Griffiths it is payback time after confirming the striker has now completed his return to first-team duties.
The 28-year-old has not featured since December due to a combination of injury and personal issues.
But, having taken time away from the club to deal with his off-field problems, he is now back among Lennon's squad preparing for the new season.
And Hoops boss Lennon is delighted with what he has seen so far this week at their Lennoxtown base.
However, the former Northern Ireland international has told the Scotland hitman it is now time he repaid the club for the backing he has been given over the last few months.
Lennon said: "He's doing very, very well. He's worked very hard and has had a good week. He's done all the training, double sessions, so we're very pleased.
"He's been training constantly for the last two or three months working on his conditioning, so we've got no problem putting him in (to the team). It's great for us. We've got a proven goalscorer at club and international level that we've missed for a significant period of time.
"He's missed it as well and he is in a good place at the minute.
"It's a credit to him that he's worked really hard away from the limelight and knuckled down. It's payback time for him because the club has been very good for him. He knows that, and he knows what he's got with me.
"Should we consider him now to have fully rejoined the first-team? Yes. He's still got a bit to do in terms of his conditioning, as they all do, but really pleased with what I'm seeing so far."
Meanwhile, David Turnbull chose Celtic over Norwich for footballing reasons and not cash, Lennon insists.
The 19-year-old Motherwell ace has finally put an end to the on-off transfer saga by agreeing a move to Celtic Park and will be unveiled once he completes a medical.
Celtic's pursuit of the Scottish Football Writers' Association Young Player of the Year has featured many twists and turns.
It looked like the Scotland Under-21 playmaker was set to make his move to Glasgow last week after the Hoops struck a £3.25million deal with Well chiefs, only for talks with Turnbull and his representatives to break down.
The Hoops then released a statement insisting they had made Turnbull a "magnificent offer" but were ready to "move on" to other targets unless the teenager had a change of heart.
With Parkhead chiefs then backing away from the deal, Turnbull flew south to meet with Canaries boss Daniel Farke after the Premier League new boys matched the package on offer from Celtic.
But the player, who scored 15 goals in his breakthrough campaign last year, has ultimately decided his future lies in a green and white jersey.
Lennon - who hopes to have further new arrivals on board by the time his team fly out for their pre-season training camp on Monday - shrugged off suggestions the dramatic chase had been frustrating.
"These things take time and some deals are quicker than others," he said.
"David had options, which he was quite right to pursue, but thankfully he's chosen us over Premier League clubs, which is quite a coup for us. We're absolutely delighted to get this one over the line. I spoke to him on a number of occasions by phone, although today was the first time I got to meet him. We spoke maybe three or four times over the summer break. Whether that had any influence you'd have to ask David.
"But we know he spoke to Norwich and the decision came after that, which is fantastic for us. He's chosen us over Norwich for footballing reasons, not financial. Trust me on that. That augurs well for the lad going forward.
"I think he sees Celtic as a great pathway for him to progress in his career and I would echo those sentiments."
Celtic will kick-off their quest for a ninth straight Ladbrokes Premiership title against St Johnstone on August 3.
The Hoops host Saints at Parkhead as they set off on their attempt to equal a feat only previously achieved by Jock Stein's Hoops of the late 1960s and early 1970s, and the 1990s Rangers team bossed by Walter Smith.
Rangers get their campaign up and running the following day as they take on Kilmarnock at Rugby Park as they aim to prevent their rivals reaching the milestone.
The first Old Firm battle of the new term could be vital and it is scheduled for Ibrox over the fourth weekend on August 31, although all dates are subject to change for television broadcast purposes.