Louis van Gaal has told Manchester United to be prepared for the challenge of a Norwich City side fighting for their Premier League lives.
Alex Neil's men were surprise 2-1 winners at Old Trafford in December but have won only four and lost 12 of their 18 subsequent matches to leave them second bottom - two points adrift of fourth-bottom Newcastle United but with a game in hand.
United have a battle on their own hands to finish in the top four and will aim to increase the pressure on Manchester City ahead of their fourth-placed rivals' crunch clash with Arsenal, who are third, on Sunday.
"It is always difficult to fight against a team that fights for maintaining their position in the Premier League," Van Gaal told a news conference ahead of Saturday's encounter at Carrow Road. "But that is no excuse.
"We have to cope with that. They have won at Old Trafford so we shall have to take revenge. It will be a tough game but we have to win."
Van Gaal will be without Marouane Fellaini for the rest of the league campaign after the Belgium international received a retrospective three-match ban for his on-field clash with Leicester City's Robert Huth during last weekend's 1-1 draw.
Fellaini will be available for the FA Cup final against Crystal Palace later this month, while Van Gaal is largely free of the injury problems that dogged his squad earlier in the campaign.
United's impressive performances against the Premier League's leading lights are a source of frustration when set against less laudable efforts this term and Dutchman lamented what might have been as he congratulated newly crowned champions Leicester.
"When you see what we have done against [the] top five, what we have done against [the] bottom five is not a good average," he said.
"The month of December caused us big damage. We have our own reasons for that because of injuries. You have to cope with that.
"I always talk about facts, not hypothetical circumstances and activities. I can only say at the end of November we were [in] first position.
"Then we had the injuries. What would have happened, you can never tell.
"Leicester are the champions. I have great respect for them and they deserve the championship."
Norwich captain Russell Martin returned from illness to feature in last weekend's 1-0 loss at Arsenal.
The defender is keen to make fellow strugglers Sunderland and Newcastle feel the heat by winning the early Saturday kick-off before the north-east duo get respective matches against Aston Villa and Chelsea underway.
"Newcastle have got two games left; for Sunderland, it's a big ask for them to win all three of their games left," Martin told the Eastern Daily Press.
"So, we win on Saturday before they have both played and we go back above them both.
"It's as simple as that. And that's what we have to go and do. Win against Manchester United and we go back above our rivals, it puts the pressure back on them.
"If we win, it swings things back in our favour again."
Key Opta stats
- Manchester United have never lost home and away to a promoted side in the same Premier League season.
- Norwich have lost five of their seven Premier League home games against Manchester United, with victories coming for City in April 2005 and November 2012.
- Wins over Manchester City and Liverpool are United's only successes in their past 10 away league games (W2 D3 L5).
- Only relegated Aston Villa (13) have lost more Premier League matches in 2016 than Norwich's 11.
- Anthony Martial scored against Norwich at Old Trafford and has 15 goals in all competitions to be United's top scorer.