Man Utd and Van Gaal need to prove a point against Liverpool

United were soundly beaten in last week's last 16 first leg at Anfield and Jurgen Klopp's hungry, high-pressing Liverpool would have put the tie out of sight were it not for the reflexes of visiting goalkeeper David de Gea.

Van Gaal enjoyed a rare rousing moment at Old Trafford on Sunday when Anthony Martial's 83rd-minute equaliser against West Ham United kept his team in the FA Cup, but a second successive non-performance against Liverpool could make it a torrid evening for the under-fire Dutchman.

"It's a big challenge, but we have to believe in it. I have spoken only to the players about victory," Van Gaal told his pre-match press conference.

"We owe always to the fans a big result because the fans are paying to see that and we have to deliver."

United's 1-1 draw with West Ham means that failure to overturn Liverpool's advantage will not signal the end of their trophy-winning ambitions this season, but the club's increasingly frustrated supporters are unlikely to forgive an approach as meek as the one witnessed in the first leg.

Van Gaal was adamant afterwards that his philosophy is working, but the evidence of the match told its own story.

Less than five months into his Anfield tenure, Klopp has already put his stamp on Liverpool's playing style, instilling a high-tempo counter-pressing game that left United chasing shadows.

In stark contrast, Van Gaal has now been at United for 20 months, and his team are still in search of an identity.

Liverpool have bounced back impressively from their penalty shootout loss to Manchester City in the League Cup final, winning three games on the spin in all competitions, and are now putting pressure on United, West Ham and City in the battle for the fourth and final Champions League spot.

United's form, meanwhile, is heading in the other direction, with a run of four wins followed by successive losses to West Bromwich Albion and Liverpool, prior to the FA Cup quarter-final draw with West Ham.

United have overturned a two-goal deficit in Europe on four previous occasions, but the status of the tie leaves them in an awkward position: obliged to attack, but knowing that an away goal for Liverpool would be fatal.

"We cannot go crazy," midfielder Ander Herrera warned on Wednesday.

Liverpool have proved themselves adept at playing on the counter-attack under Klopp, notably in the slick away wins over City and Chelsea prior to Christmas.

But the German is adamant that his team will not sit on their lead and has challenged his players to approach the game with even greater intensity than the first leg.

"We know that we know how to play them," said Klopp.

"A good start in the game is important. It's not the most important thing, but we will try to play similarly or more intensive than we did at Anfield.

"It was a good night for us last week, but at the same time it's only halfway."

United winger Jesse Lingard is available again after missing the first leg through suspension, but although Bastian Schweinsteiger made his return from a knee injury as a substitute against West Ham, Van Gaal says that he is not yet ready to start.

Cameron Borthwick-Jackson, Ashley Young and Antonio Valencia are not fit enough to feature at all despite having returned to training after injury, while captain Wayne Rooney, Luke Shaw and Phil Jones remain sidelined.

Liverpool, who took up the option of training at Old Trafford on Wednesday, have had a clear week to prepare for the return leg and Klopp reported no new injuries.

James Milner has recovered from the virus that caused him to miss the first leg and is an option if Klopp decides to bolster his midfield.