Manchester United's failure to score an away goal against bitter rivals Liverpool has left them with a handful to do in the second leg next week, defender Chris Smalling said after Thursday's 2-0 last-16 Europa League defeat at Anfield.

Winning Europe's second-tier club tournament appears to be United's best chance of qualifying for the Champions League next season but goals from Daniel Sturridge and Roberto Firmino either side of halftime has severely dented their hopes.

"We're disappointed. I think we could have done with getting an away goal -- we know we've got a difficult job on our hands," Smalling told the club's website.

"We could have really done with getting that away goal. I think if you get that goal, you can be a bit more positive, but it's now up to us to rectify it in front of our own fans. The first goal is going to be crucial."

Louis van Gaal's men are sixth in the Premier League, three points behind fourth-placed Manchester City, who have a game in hand.

United's most likely hope of any silverware this season will be the FA Cup and they host West Ham United in the quarter-finals on Sunday.