Matteo Darmian
Darmian was taken off on the hour mark with what looked like a rib injury.Getty Images

Manchester United manager Louis van Gaal will ratchet up attempts to sign a full-back during the final week of the January transfer window after Matteo Darmian was a taken to hospital after being taken off in the Premier League defeat to Southampton. The Italian was replaced by Paddy McNair on 60 minutes after a collision with Shane Long, leaving the club without a recognised senior full-back.

Charlie Austin buried a second half header less than eight minutes into his Saint debut to consign United to their fifth home league defeat of the season, after they failed to net in the first half for an 11th straight game at Old Trafford. The home side mustered just one shot on target and have now netted just 12 times on their own turf this term.

Defeat sees United slip five points off the Champions League places and ten adrift of the top of the Premier League table. The full-time whistle was accompanied by a chorus of boos from the United support and Van Gaal accepts the criticism is justified.

"It was not good today," he told Sky Sports. "We lost and you knew our defence with set plays became every minute weaker because I have to change players and that was our problem in the last minute. It was a poor game as we could not create chances. Our opponent had few chances so it was more or less a 0-0 game but at the we have lost.

"[The lack of chances] that is also because of the organisation of our opponent, who plays with five defenders and are very compact but still we have to create chances. When you analyse the game that is my answer. You cannot say that they [the fans] are not right and of course they are disappointed and they have the right to boo me. We have to stick together in this period because we have a lot of injuries."

United are yet to confirm the nature of the injury suffered by Darmian, however the player has been taken to hospital after he was left spitting blood by the challenge with Long. Luke Shaw, Marcos Rojo and Ashley Young are all out injured and it leaves the Dutch coach with wafer-thin options.

"Yes [the injury to Darmian was a turning point]," the United boss added. "In the second half we started very well and the crowd was behind the players but then the injury of Darmian was not very nice to see that. That plays a role but it is no excuse.

"Darmian is the fifth full back who is injured so that is also a problem but also I knew in advance that the opponent shall play in that system [3-5-2]. When we play 4-3-3 it is very difficult to beat them because in transitions they have a lot of pace and also a lot of chances.

"Yes but with Darmian that was already the case [wanting to sign a full back in January]. We have to wait and see. We have to wait and see [on Darmian] he is in hospital but it is not very nice I can assure you."