Manchester United manager Jose Mourinho targets Bayern Munich star David Alaba in January

Manchester United manager Jose Mourinho is keen on completing two defensive signings in the January transfer window. He has set his sights on Bayern Munich star David Alaba and Southampton defender Virgil van Dijk.

The Portuguese tactician has questioned Luke Shaw and Chris Smalling's ability to play through the pain after his side's 3-1 win over Swansea City. The two have not featured in recent times with the former Fulham man out of action with a reported toe injury.

According to the Mirror, Mourinho wants the same backing from United executive vice chairman Ed Woodward in the mid-season window. The Red Devils' scouts have watched Alaba twice in action, while on international duty with Austria.

Alaba played the full 90 minutes in his national side's 1-0 defeat to the Republic of Ireland in the World Cup qualifier. He even came on as a second half substitute in a goalless draw against Slovakia in the international friendlies.

The Bayern star, who can operate as a left-back or in the midfield has emerged as a key target for the Old Trafford outfit's manager. He is believed to be valued around £40m ($49.6m) and is attracting interest from United. The Bundesliga winners are unwilling to let their star players leave the club at the start of the year

The same report also claims that the 20-time English champions are not the only club interested in securing his signature. United's derby rivals Manchester City are also in the race for Alaba, who played under their current manager Pep Guardiola at the Allianz Arena. In addition to this, Arsenal also considered an option in signing Bayern's versatile star.

Smalling and last summer's signing Eric Bailly are recovering from their injuries, forcing Mourinho to field Phil Jones and Marcos Rojo as his centre-backs. The Argentine international and Matteo Darmian's future at Old Trafford remains uncertain and the former Chelsea boss is looking to bring in one more central defender in January.

Meanwhile, Van Dijk's rise at Southampton this season has helped him draw United's attention. However, any move for the Saints defender will see the Red Devils spend around £30m ($37.2m) in January.

Bailly will be part of the Ivory Coast squad for the African Cup of Nations. Mourinho will miss the former Villarreal man and completing the signing of Van Dijk could boost United's back four for the second half of the season.