GoalkeeperDavid De Gea continues to see his stock rise and the Spaniard has been one of the best goalkeepers in the Premier League so far this season. Despite the free-transfer signing of compatriot Victor Valdes, De Gea will keep his place between the sticks for the foreseeable future.DefenceIf Van Gaal reverts to a back four – which coincided with some of United’s best football this season – Phil Jones will likely be deployed at right-back with Rafael set to miss the game with a facial injury.Shaw is fit again and expected to retain his place and face his former club for the first time since transferring to Old Trafford in the summer.MidfieldDi Maria hasn’t started since November but returned last week at Huish Park with a well-taken goal. The Argentine excelled in a midfield three at Real Madrid, and with Michael Carrick back and Ander Herrera beside him, Van Gaal might finally be able to field what many consider his best midfield three.AttackRadamel Falcao’s hit-and-miss form could prompt a re-think up top but the Colombian has shown signs that he’s starting to adapt to the rigours of English football.Captain Wayne Rooney was dropped into midfield in recent weeks – where many feel he will end his career – but ineffectual performances against Stoke and Yeovil should see the Englishman pushed further forward to provide a threat alongside Falcao and Van Persie.Possible 3-5-2 Man United line-up against Southampton: 1 1 1 DefenceInjuries continue to blight United’s season and Van Gaal has opted for three at the back to combat the loss of players.However, United’s defence look lost in the system. Rarely have the Red Devils played worse than they did at Southampton last month and it would be a risk to retain the model against the Saints again.But if the Dutchman does continue with 3-5-2, Jones, Chris Smalling and Jonny Evans will likely form the back three, although Marcos Rojo is close to a return, while Shaw and Antonio Valencia would provide the width down the flanks.MidfieldRooney’s two-goal performance against Newcastle drew comparisons with Paul Scholes and he could partner Di Maria in the middle and be given the license to drive forward with the protection of Carrick behind.With Di Maria’s return to fitness, Juan Mata looks the likely individual to miss out despite a good run in recent weeks, while the Argentine would inject pace which has been lacking in United’s attacks.AttackVan Persie missed out on the win at Yeovil and the rest could be just what the Dutchman needed to rejuvenate him heading into the second half of the season.Falcao needs to continue in the starting XI and there are signs that he is adjusting to life in the Premier League.Man United fans, how do you think you’ll line up against Southampton? Comment below… Manchester United look to continue their 10-match unbeaten run in the Premier League when they host Ronald Koeman’s impressive Southampton side on Sunday.Last month, Robin van Persie’s two goals settled the game between the two sides at St Mary’s in a contest largely dominated by the Saints.United remain undefeated in the league since the loss at rivals Manchester City in November, while Southampton travel to Old Trafford in positive mood having won three of the last four league matches.The Red Devils are boosted by returns for Angel Di Maria – who scored in last weekend’s FA Cup tie at Yeovil – while Luke Shaw is set to return against his former employers. Will Di Maria start and could Louis Van Gaal revert to a back four with players returning to fitness? talkSPORT takes a look…Possible 4-4-2 diamond Man United line-up against Southampton: Manchester United look to continue their 10-match unbeaten run in the Premier League as they host Ronald Koeman’s impressive Southampton side on Sunday.