Gaitan is Ferguson's No 1 target in January

United track £39m Benfica schemer after Champions League exit and loss of Vidic

Manchester United have stepped up their interest in the Benfica midfielders Nicolas Gaitan and Javi Garcia, placing their discussions with the Portuguese side on an official footing in an attempt to prevent other clubs getting in ahead of them.

United have asked Benfica, who advanced from United's group into the Champions League knockout stage, to notify them of any moves from other clubs for either of the two midfielders, both of whom impressed in this autumn's fixtures against Sir Alex Ferguson's side. Benfica have told United that Gaitan, 23, who has a £39m release clause, has been the subject of interest from Valencia. Garcia, who has been widely linked to Arsenal and Internazionale in the Portuguese press, does not carry the impediment of a release clause though Real Madrid, who nurtured him as a youngster, do have first refusal on a player who has emerged as a candidate for Spain's Euro 2012 squad.

United scouts watched both Gaitan and Garcia at Benfica's recent matches against Naval and Sporting Lisbon matches specifically to develop a clearer picture on them, rather than to prepare for United's encounter with Benfica on 22 November, in which both played.

Ferguson insisted yesterday that "it is not a consistent route for us to buy in January simply because of all the disadvantages", and Benfica have indicated to United that they will not encourage any transfers until next summer. But Ferguson did not preclude the idea of reinforcing, as he did by signing Patrice Evra and Nemanja Vidic in the winter of 2006 after United's last Champions League group stage exit.

Though the United manager has options in central defence to cover for Vidic, who has been ruled out for the rest of the season with cruciate ligament damage, there are chronic problems in midfield. Tom Cleverley will possibly not be back until well into the new year and Anderson is out until February; Michael Carrick and Darren Fletcher have struggled.

Garcia, 24, operates in front of the defence, though is a ball-player who also likes to advance and score – rather too much for the liking of Benfica coach Jorge Jesus. Though United look like a side in need of a playmaker – the role Gaitan held at Boca Juniors before his €8.4m (£7.1m) move in the close season – Jesus has deployed Garcia in a left-sided berth with which he is actually less comfortable. The view from within Portugal is that Benfica may try to keep him at the club for another season if they win the domestic title.

Gaitan has already been the source of intense transfer speculation in Portugal, linking him to most of Europe's elite sides. Ferguson's tendency to sign players who have performed well against his own club – Cristiano Ronaldo and Phil Jones among them – may have made the Argentine's display against United in September significant. A new contract he signed in October keeps his release clause at £39m and it is considered unlikely that Benfica would be willing to accept less. Some Portuguese observers consider Gaitan to be an even better prospect than his compatriot Angel di Maria, who left for Real Madrid in 2010.

Ferguson yesterday raised the previously improbable prospect of Rio Ferdinand playing for a third time in seven days, against Wolves today, as Vidic prepares for a meeting on Monday with a specialist.