PARTICK THISTLE boss Gary Caldwell is adamant veteran striker Scott McDonald is fitter now compared to when he was starring for Celtic in the Champions League.

The 35-year-old’s playing days appeared to be over when he departed Dundee United last summer, with the former Australia international failing to secure another club and focusing increasingly on his media work.

However, his ex-Hoops teammate Caldwell convinced him to pen a short-term contract at Firhill in February and he has been richly rewarded, with McDonald hitting the ground running with four goals in six appearances.

And Caldwell has nothing but praise for McDonald’s fitness levels, insisting that - while he may have notched 64 goals and won two major honours with Celtic – he has never been in better shape.

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“I had lunch with Scott McDonald and I knew straight away that he could make a difference at Championship level and he has been sensational,” said Caldwell.

“I went into the gym recently to speak to the boys who had been playing and were doing a recovery session - and Scotty was on a treadmill, running, sweat pouring off him.

"I was worried about him because we had three games in a week coming up. I said ‘what are you doing?’ and he just told me that he wanted to keep on top of things - and he is far fitter now than he was when he played for Celtic.

“He’s still got that heavy backside that he can stick into centre-halves! That still works for him, but he is leaner, moves much freer. I think that’s just experience.

“As we all get older in our careers, you get a little bit lighter, a little bit fitter - you understand your body and realise what needs to be done to be successful.”

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McDonald’s arrival was part of a mid-season revolution that saw nine players arrive and seven depart Thistle, including, most contentiously, fans’ favourite Chris Erskine.

Caldwell believes Erskine’s move to Livingston has benefitted all parties after revealing that he bumped into the winger at the weekend.

“I was speaking to Chris at Kris Doolan’s induction into the Hall of Fame on Saturday night. We had a good chat,” added Caldwell.

“It was a really difficult one because Chris Erskine is a very good player, was an unbelievable servant to Partick Thistle and fans’ favourite for many years. He will always be welcome back and the supporters will always hold him in high regard.

“It was just one of those decision I felt I had to make and, as I said when I spoke to him on Saturday night, I think it was a move that worked for everyone - the player, Livingston and Partick Thistle.”