Manchester United's move to sign playmaker Luka Modric looks to be increasingly complex. The club had appeared favorites to secure the Tottenham man earlier in the summer, but that position now looks to have been taken by Real Madrid.

The La Liga winners have been increasingly linked to Modric in recent days, with his reported friend and former teammate Mate Bilic suggesting that a move was imminent. The latest speculation comes from the Mirror, which claims that the 26-year-old has asked for a move to the Bernabeu. Any quotes are conspicuous by their absence from the piece, however.

There is a similarly spurious-appearing story in the Sun. The tabloid alleges that Lokomotiv Moscow will make a push to sign Modric, with the idea that he will link up with his former Croatia coach Slaven Bilic who has just taken over at the Russian club.

Despite the plentiful supply of money in Russian football, it is difficult to envisage Modric moving to a club who will not be playing Champions League football next season.

There has also been further speculation about another reported United target, James Rodriguez.

According to Portuguese publication O Jogo, the Porto winger is also interesting United's rivals Liverpool. That competition is unlikely to unduly worry United, however. The main obstacle appears to be Porto reportedly holding firm over the £40 million buyout clause in the Colombian's contract.

Rodriguez's agent Silvio Sandri recently revealed that his client's situation was complex and that he would soon be meeting to discuss matters with Porto's directors.

A left-footed wide man with an eye for goal, Rodriguez has been mentioned as a possible replacement for Nani, who has yet to agree a new contract.

United's other main area of interest in this summer's transfer market appears to be the signing of a left back. Leighton Baines has been strongly linked to provide competition to Patrice Evra, although Everton's reported £20 million asking price would appear to rule out a move.

Ferguson is also said to be interested in Valencia's Jordi Alba. It is widely believed that the Spanish international is on the verge of a move to Barcelona, but Setanta Sports claims that United will try to make a late push for his signature as Valencia and Barca haggle over a fee.

Alba, 23, has started all four of Spain's matches thus far at Euro 2012 and is thought to be available for £12 million.

A further possible target for the left-back position has emerged in recent days with Metro alleging that United scout Martin Ferguson has watched Jetro Willems during all three of the Netherlands' games at Euro 2012.

Although the 18-year-old has potential, it is unlikely that Sir Alex's brother would have come away from the tournament with glowing references for Willems, who looked badly exposed, admittedly in a woeful Dutch side.

Willems played 15 games for PSV in the Eredivisie last season and would reportedly be available for £10 million. Metro also links United with left-backs Georgi Schennikov of CSKA Moscow and Bordeaux's Benoit Tremoulinas.