Ricky Van Wolfswinkel's agent has confirmed that Manchester United and Chelsea are watching the Dutch striker.
The 22-year-old was heavily linked with a move to England in the summer, before Sporting Lisbon swooped in a €5.4 million raid on the FC Twente striker.
Van Wolfswinkel's value has since doubled after hitting seven goals in nine Primeira Liga games this term, with Barclays Premier League interest once again stirred in the forward.
Manchester United first team coach Mike Phelan confirmed last month that the Red Devils were keen on the player, with the club's scouts dispatched to track his progress in Portugal.
Chelsea have also been credited with an interest in the last week, and agent Louis Laros confirmed that the pair had both been keeping tabs on the player.
"I know they (Manchester United and Chelsea) are watching him but that is not unusual because they are watching all the best young players in Europe," he told the International Business Times.
"I do not envisage a move in January though as I have not heard anything. I think it would be almost impossible but you never say never in football."
Chelsea boss Andre Villas-Boas is also thought to be monitoring Sporting teammate Elias ahead of a possible double January bid, but it's the striker which has captured the imagination of the British media.
With uncertainty remaining over the future of Nicolas Anelka and Didier Drogba at Stamford Bridge, the Blues are tipped to be in the market for a new striker in the New Year, with Van Wolfswinkel now at the top of the Chelsea list.
His connection to former Chelsea chief executive Peter Kenyon is another interesting twist that could potentially favour a move to the capital, although Villas-Boas knows competition will be fierce for the signing.
Manchester United will not be willing to let their rivals snap-up the player from the Estádio José Alvalade, with The Daily Mail reporting yesterday that an £11 million fee could be the figure that leads to a move.
Jordan Rhodes, Edinson Cavani and Ezequiel Lavezzi have also been linked with moves to Old Trafford in recent months, suggesting a player in the forward position is in the mind of the Manchester United boss.
Sir Alex Ferguson does have plenty of players at his disposal in the position though, with Wayne Rooney, Javier Hernandez, Dimitar Berbatov, Danny Welbeck and Michael Owen all fighting for first team opportunities within the Manchester United side.
Van Wolfswinkel would add further to the plethora of attacking talent, but it remains to be seen if either Ferguson or Villas-Boas can persuade Carlos Freitas to sell.