Bayer Leverkusen cannot compete with Manchester United over Rene Adler signature - Rudi Voeller

Sir Alex Ferguson still keeping tabs on other 'keepers, according to agent
Former Germany boss Rudi Voeller has admitted his concern that Bayer Leverkusen will be unable to extend the contract of goalkeeper Rene Adler should Manchester Unted lodge a serious offer.

The player's contract - rumoured to include a clause that allows the 18-times Premier League winners to purchase the player for a fee in excess of £20 million - expires in 2012, but Voeller, director of sport at the German club, hopes that Champions League qualification could encourage the highly rated stopper to commit to a new contract.

"We will of course try to extend [Adler's contract] - within our means," said Voeller to Kicker.

"We know that for Rene, from a sporting perspective, whether we play internationally is important. Of course we want to play in the Champions League, and this is indeed the goal of Rene."

However, Voeller admitted: "We cannot keep up with Manchester United."

Leverkusen's hopes of clinging on to the player may rest on United looking elsewhere for a replacement for veteran Edwin Van der Sar.

"Rene is not the only goalkeeper that [Manchester United] have observed," said Voeller. "We stand in good conversation with Rene and his advisers."

In addition to the 25-year-old Adler, United have been linked with Pepe Reina, Manuel Neuer, David de Gea and Maarten Stekelenburg.

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