Former Liverpool manager Graeme Souness has claimed that Louis van Gaal does not currently know his best team at Manchester United.

The Red Devils are currently fourth in the Premier League but have come in for criticism in certain quarters for their performances at times throughout the campaign.

United host Tottenham Hotspur on Sunday before games against Liverpool, Manchester City and Chelsea, and Souness thinks that Van Gaal's side need to improve their displays if they are to stay in the Champions League spots.

"This period is vital, so far this season it's not the way they would have wanted it, they've been digging out results but scratching for performances," he told Sky Sports News.

"They've chopped and changed their team and system so much, [Van Gaal] has used 31 players already this season and players like continuity.

"It's a very very difficult job he's got because of the all the places you have to play with a panache and style, it's here [at Old Trafford] and he's struggled to do that and here we are now in the middle of March and he's not done that so far."

United were knocked out of the FA Cup by Arsenal at the quarter-final stage on Monday.