Manchester United could capitalise on stalled contract negotiations to seal a deal for Sporting star Ricky van Wolfswinkel.

The Portuguese club had hoped to tie the Dutchman down to a long-term contract - complete with a hefty buyout clause - but talks have hit a stumbling block, according to talkSPORT.

Van Wolfswinkel's agent, Louis Laros, has confirmed that both sides are yet to reach an agreement, opening the door for a possible switch to Manchester United.

However, Manchester City are also rumoured to be interested, and both clubs could spark a bidding war for the talented forward.

Van Wolfswinkel has enjoyed an impressive debut season in Portugal, having moved from FC Utrecht for £4.5million last summer.

The Sporting ace has hit 14 goals in 25 league appearances, and netted another six in the Europa League, prompting interest from both Manchester clubs.

Laros insists that the ball remains in Sporting's court and a deal may still be reached, but admits that there is interest in his player from overseas.

"We are waiting for Sporting," said Laros. "There is still no progress in increasing the value of the buyout clause that the club want to include.

"I have heard rumours in the media about interest in the player from foreign clubs."

With Sporting reportedly eager to up the buyout clause, City and United may move early to try and seal a cut-price deal for the Netherlands international.

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