Celtic boss Ronny Deila is determined to keep hold of last season's PFA Player of the Year Stefan Johansen during the January transfer window.

The creative midfielder has been linked with a move to Aston Villa but the Norwegian is keen to keep him in his squad.

It comes as Deila confirmed Croatian youngster Ljuban Crepulja has joined the club on trail. The midfielder, who has six months remaining on his contract with Slaven Belupo, has a week to impress the Celtic coaches.

Meanwhile, new signing Erik Sviatchenko is set to return home from Denmark on Friday but will not be available for selection this weekend when the champions welcome St Johnstone to Parkhead.

"We want to keep every player, things come up every day now that I haven't heard about," Deila said. "Stefan Johansen is staying here, we want to keep him of course.

"[Crepulja] is a player we have watched a little bit and that we want to see more of, now he is training with us. We will see during the week what we do further.

"[Sviatchenko] is coming tomorrow and he will be at the game but he will not be available to play. It is too early and he needs to train with the team before he gets his debut."

The Celtic boss says the Scottish FA's draft youth system could provide a pivotal stepping stone between playing for the Under-20s and first-team.

The proposal, which is being backed national manager Gordon Strachan, would see a new system for loan deals between Premiership and Championship teams in a bid to improve first-team game time for young Scottish players.

While Ronny Deila says Celtic have never had a problem loaning out potential talent for senior experience, it's a set-up which could prove successful across the SPFL.

"It's important that the youngsters get experience and get a chance," he said.

"That's why we rent out a lot of our younger players when they come to a stage of having trained with the first team, played with the U20s and need a new step in between.

"Other clubs are in the same situation as well. It's always positive to co-operate with other clubs and do what's best for Scottish football."