LONDON: Misfiring Manchester United must show some fighting spirit against third-tier Shrewsbury Town in the FA Cup on Monday night if they want to avoid a second successive season without a trophy, defender Chris Smalling has said.

The 20-times English champions sit six points off the top four in the Premier League, with their last two outings ending in damaging defeats that have cranked up the pressure on manager Louis van Gaal amid angry chanting from the stands.

They lost to relegation-threatened Sunderland before Thursday's 2-1 Europa League defeat by Danish club Midtjylland and Smalling wants a positive reaction from his team mates.

"The aggression that you start the game with is something you need to match with the other team, something I don't think we have done recently," he told the club's website.

Van Gaal, heavily tipped by British media to be replaced by former Chelsea manager Jose Mourinho, said his team needed a reaction in the fifth round cup match against Shrewsbury.

"We have to make them fear again," he said. "You cannot continue with losing games and the question is how we lift ourselves."