Celtic watch Serbian defender Aleksandar Pantic

Ronny Deila has re-ignited speculation linking Celtic with a move for Serbian defender Aleksandar Pantic after watching him in action for Eibar in Seville on Sunday.

The 23-year-old centre-half is currently on loan at Eibar from Villarreal, where his contract is due to expire at the end of this season.

Pantic, who joined Villarreal from Red Star Belgrade in 2013, has previously been scouted by Celtic and a host of other clubs from England, Italy and Germany.

Deila’s presence at Eibar’s 4-0 La Liga win at Real Betis suggests Pantic could be a target for the Scottish champions, although they have also been credited with an interest in strikers Sergi Enrich and Borja Gonzalez. The latter is on loan at Eibar from Atletico Madrid and scored in Sunday’s victory.

Former Celtic striker Andy Walker, who has been highly critical of his old club’s form this season under Deila, believes reinforcing the front line should be a priority for the manager during the current transfer window.

Sky Sports pundit Walker feels Celtic are dangerously reliant on top scorer Leigh Griffiths who returned from injury to score his 20th goal of the season in the shape of a 90th minute winner against Partick Thistle on Saturday.

Walker would also like to see Deila relax his commitment to his favoured 4-2-3-1 formation and deploy two men up front on occasion.

“I think they would like to bring in another striker,” said Walker. “Let’s say Leigh Griffiths was to pick up a more serious injury, Celtic would be struggling up front.

“He [Deila] could shake it up a bit. Celtic are renowned for their striking partnerships down through the years.

“I played with one myself in Frank McAvennie who was a terrific player. Larsson and Sutton were here not so long ago.

“Nadir Ciftci, if Leigh Griffiths is injured, certainly needs a bit of help. He’s not the type of striker who can play on his own up front.

“Leigh Griffiths has been terrific but is not quite 100 per cent fit at the moment, although still able at the weekend to come on and get the all-important winner.

“So I think the supporters would like to see a bit of flexibility from the manager in the way he plays.

“They would certainly like to see some better recruitment. When you look at the amount of money Celtic do spend, in getting the likes of [Stefan] Scepovic and [Derk] Boerrigter in – that’s the best part of £5 million. When Celtic spend that kind of money you expect to see a bit of evidence on the park that they are improving but those two players, for a lot