Rangers have been warned that Bolton are waiting in the wings in case the Sotirios Kyrgiakos transfer collapses.
The Greece defender moved to Ibrox on a six-month loan deal from Panathinaikos in January, but concluding a permanent transfer has proven problematical.

And Bolton boss Sam Allardyce told the Manchester Evening News: "We have had an eye on the player for quite a while, but we've not taken it any further.

"We have been watching what he's been doing with great interest."

The 25-year-old Kyrgiakos is on Confederations Cup duty with his country while Rangers continue negotiations.

"I know nothing about the situation between them and Panathinaikos," said Allardyce.

But it would be fair to say that Kyrgiakos has interested me for some time."

Rangers have the option of paying an additional £1m on top of the £500,000 already paid.

And the Scottish champions last week dismissed suggestions by agent Phanis Klonopoulos that Panathinaikos had taken back the player and would sell him to another club.

"Discussions with the player's actual representative are ongoing," said a club spokesperson, who stressed that Klonopoulos had no involvement in the latest talks.

"Panathinaikos is well aware of the contractual situation with regard to the player and, indeed, that Rangers FC currently holds the player's registration."

Kyrgiakos moved to Rangers in January and helped the Glasgow club win the title.

He wanted to return to Rangers, but there have been reports that the Scottish champions were trying to drive down the price following concerns over an old knee injury.

Kyrgiakos had arrived at Ibrox as a replacement for Jean-Alain Boumsong after the Frenchman was sold to Newcastle United for £8m in January.

Rangers this month completed the signing of Hibernian captain Ian Murray on a free transfer and the Scotland international is able to play at the back.

But he is not a traditional centre-half in the mould of Kyrgiakos.

Meanwhile, reports have suggested that Aston Villa and Middlesbrough are among the clubs interested in Rangers midfielder Dragan Mladenovic.

The Serbian international spent the second half of last season on loan at Real Sociedad.