THERE are fair few players in the modern day game whose willingness to play on while carrying a knock or nursing a strain could easily be called into question.

But Kieran Tierney, the left back who has been a virtual ever-present in the Parkhead first team since breaking through three-and-a-half years ago, could never be accused of lacking commitment to the Celtic cause.

His devotion to his club is why Brendan Rodgers knew the defender was genuinely struggling when he started to experience difficulties during training at Lennoxtown in the middle of last month.

“Kieran’s a real throwback,” he said yesterday as he spoke in depth for the first time about the injury problem which has kept the defender on the sidelines since the Europa League group game against Salzburg.

“He’s a wonderful talent and a great kid to work with. You know when he is in pain and he really is in pain. You could see in training he was pushing and giving everything, but he wasn’t quite right.

“One of his great strengths is his physicality and his power and running ability and when that’s affected it takes away a big part of his game.”

Tierney’s extended absence has been keenly felt by Celtic – not least in the 1-0 defeat at the hands of Rangers at Ibrox in the final Ladbrokes Premiership game before the winter shutdown at the end of December.

However, Rodgers stressed the 21-year-old is unlikely to require surgery to address the issue and expressed hope he will return to training at the beginning of next month – just before the Europa League last 32 double header against Valencia.

“I’m told the earliest he will be back will be the start of February,” he said. “He’s seeing the medical team and they are assessing him. He’s doing work in the gym, but he’s not out running as of yet.

“It (an operation) is not something that’s been mentioned. There’s periods of work and periods of rest and scans to see the reaction. It’s in his pubic area. The medical guys are saying it will just take time. We hope he is back soon.”

Rodgers revealed the three-time PFA Scotland and SFWA Young Player of the Year had found not being involved during his lengthy spell on the sidelines to be demanding.

“He’s been on such a run for the last few years,” he said. “He loves training and he loves playing games. Football really is his life and for him not to be out there playing is tough.

“But he’s focused on getting back and into the best condition he can be. Hopefully it will be soon because he is a player we miss. He is a player of real quality and we miss him when he is not available. He’s a player with a great career ahead of him.”

The extensive injury list Celtic currently have – Odsonne Edouard won’t be available to face St Mirren at Parkhead tomorrow evening due to his abductor strain, Olivier Ntcham is out for several weeks with a hamstring injury and Anthony Ralston has undergone a scan on the ankle knock he suffered at the weekend – isn’t the only thing that has required Rodgers’ attention of late.

He attended the meeting of Premiership managers and referees’ representatives at McDiarmid Park in Perth called by SFA chief executive Ian Maxwell last Thursday evening and offered his views on how to improve officiating in this country.

Rodgers is an advocate of referees going full-time, but, after Scott Sinclair was denied a hat-trick in Celtic’s William Hill Scottish Cup game against Airdrie on Saturday when a goal was wrongly ruled offside, he believes the SFA and SPFL must make introducing VAR their priority

“If you can’t do both then you would have to do VAR,” he said. “At least then, at every ground, you would get the decision right. For example, with us at the weekend, with Scott’s goal. They could easily go back on that and see it was a good goal.

“If you can get the two things through, great. If you couldn’t, and finances allowed one, then for me you have to go with VAR all day long.”

Rodgers added: “I think everyone would want to see that (professional referees) But it’s very difficult if the finances aren’t there. If you have guys who are in a really good professions, and they’ve been asked to go full-time on 50-70 percent less money, you’re not going to do it, are you? It’s common sense, really.

“I think all the refs would love to be full-time. So I think common sense would say they would want it all, to go full-time and have VAR. But if you don’t have the clout financially to do it and you have to choose one or the other then for me it has to be VAR.

“It is coming in European football. If you are playing here with no VAR and then go in to Europe where there is VAR, the things you get away with when the eyes are not watching will be different.”