David de Gea wants Manchester United to prove it can thrive in challenging environments by beating West Ham at the London Stadium on Sunday.
United heads south after recording two successive 1-0 victories, first over Leicester City and then Astana in the Europa League in midweek.
Both wins were secured at Old Trafford, as was the opening-weekend trouncing of Chelsea.
Ole Gunnar Solskjaer's men have only travelled twice this term – to Wolves and Southampton – and had to settle for a pair of 1-1 draws.
Those results and last season's 3-1 loss to the Hammers in London have goalkeeper De Gea demanding focus ahead of a tough test.
"I believe they have a decent side with some good players who are important to them," the Spain international told his club's website.
"They are on the up at the moment, but we still have bad memories from last season, so we have to be much more switched on right from the off than we were then.
"There are three very important points at stake for us to remain up there near the top and also for the younger lads to keep gaining in confidence.
"We also want to show that's what we're here for, going away to difficult grounds and going there for the three points."
United has not won away from home since a second-leg upset of Paris Saint-Germain in the last 16 of the Champions League in March.
West Ham is unbeaten in five matches in all competitions and sits level with the Red Devils in the Premier League on eight points.