Following the signing of Robin van Persie last week, Manchester United have further added to their squad on Tuesday. In have arrived two players purchased with an eye to the future in Dutch left-back Alexander Buttner as well as young Chilean forward Angelo Henriquez. But, as they try desperately to reclaim the Premier League title from neighbors Manchester City, there could yet be more signings before the close of the transfer window at the end of the month.

Monday's defeat to Everton highlighted deficiencies that still exist in Sir Alex Ferguson's squad; here are five players that may be recruited to address them.

Axel Witsel (Benfica)
United have been linked to the all-action Belgian midfielder for some time, following an excellent debut season in Portugal with Benfica. It has long been apparent that United lack a driving force in midfield to complement the playmaking skills provided by the likes of Michael Carrick, Paul Scholes and now Tom Cleverley. Witsel could be the man to provide just that and at only 23 he still has ample potential.

With Benfica possibly seeking as much as €30 million (£23.7m) for his signature he would certainly be a lucrative addition. But, having just spent £24 million on a forward, Sir Alex Ferguson must face serious questions were he not prepared to pay at least as much for a player whose qualities are far more necessary at Old Trafford.

Hector Herrera (Pachuca)
The 22-year-old midfielder has just returned from the Olympics where he played an important role in Mexico's historic gold-medal triumph. His performances in Britain followed up his claiming of the award for the best player at this summer's prestigious Toulon tournament-where Mexico were also victorious.

Herrera's possesses the combination of energy and technical skill that would go down well in a United midfield that has been found wanting for several seasons. His Mexican club, Pachuca, have just revealed that United have made an official approach, meaning a deal could still happen before the deadline.

Kurt Zouma (Saint-Etienne)
The 17-year-old defender has emerged as a target for United in recent days as L'Equipe claimed that the club had sent scouts to watch him in action for Saint-Etienne. Sir Alex Ferguson has always shown a willingness to snap up young talent when it becomes available and with Chelsea and Queens Park Rangers also said to be monitoring the Frenchman, he may now decide that now is the time to make his move.

Although he is sure to be one for the future, as Monday's defeat at Everton showed, United could do with all the help they can get at center-back right now.

Moussa Dembele (Fulham)
United are reportedly one of a number of clubs-including Real Madrid and Chelsea-to have made an approach for the versatile Belgian this summer. Although originally signed by Fulham as a forward, the 25-yar-old blossomed in a central midfield role last season, which is where he could be a useful presence for United.

With an impressive engine and excellent dribbling skills combined with an underrated tackling ability, he may offer much of what Anderson has so far failed to produce on a regular basis.

Cheick Tiote (Newcastle)
Although lacking the same technical skill and threat going forward as Witsel, Tiote would also add a combative element to United's midfield. The Ivorian has been an impressive figure on Tyneside since signing form FC Twente two years ago.

A recent report from the Daily Mirror claims that United have watched the 26-year-old for some time and Newcastle are braced for a bid before the close of the transfer window. However, with Chelsea also said to be interested and Newcastle known for driving a hard bargain, Ferguson may look elsewhere.