A late goal from Kortney Hause secured the visitors all three points at Old Trafford as the Reds fell to our first defeat of the Premier League campaign.
There was, however, nothing De Gea could do about the goal from the corner, having been impeded by an offside-placed Ollie Watkins in the build-up.
After the cruel end to a tense affair at the Theatre of Dreams, the 30-year-old Spaniard spoke to MUTV to assess the performance.
"It's a very disappointing day for us," De Gea told club media.
"I think there's no excuses today.