David de Gea is looking for West Ham redemption after Manchester United's chastening defeat at the London Stadium last season.
The Hammers cruised to a 3-1 victory that day with Ole Gunnar Solskjaer's side making the trip to the capital on Sunday looking for a first away win in all competitions since their Champions League last-16 victory at Paris Saint-Germain in March.
United's six successive winless league matches on the road is one short of their Premier League record - although they are looking to build on back-to-back wins going into the encounter.
"I believe they [West Ham] have a decent side with some good players who are important to them," said De Gea.
"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."