Lisandro Martinez has claimed that Manchester United were "playing so well" before losing 3-0 to Bournemouth on Sunday.
Ruben Amorim's side went into the fixture at Old Trafford looking to build on the previous Premier League victory at Manchester City.
Instead, the Red Devils succumbed to a one-sided reverse at the hands of the Cherries, who have moved into fifth position in the Premier League table in the process.
United have now lost three of their last four fixtures in the top flight, also going down to Arsenal and Nottingham Forest to leave them in 13th place.
Nevertheless, Martinez was of the opinion that United were impressing at the Theatre of Dreams before conceding goals either side of half time.
"We create many chances"
Speaking to MUTV, the Argentina international has backed Amorim and his teammates to turn things around quickly.
He said: "We are very disappointed because I think we're playing so well, we create many chances and unfortunately we couldn't score, so it's disappointing.
"We have to adjust a few things, especially at set-pieces and we have to start the games by scoring the first goal.
"We will work on that, I think we have a great coach and a great group as well. At this club, losing is unacceptable but we are here to change things."
United had 23 shots on goal, seven of which were on target. By comparison, Bournemouth found the target with five of their 10 efforts.
Furthermore, United also had 45 touches inside Bournemouth's penalty area, in excess of three times more than Bournemouth's 14.
A chance to turn a corner
United have kept just one clean sheet in their nine matches under Amorim, yet they have only failed to score away at Arsenal and against Bournemouth.
Seventeen goals have still been scored across the other seven fixtures ahead of facing a Wolverhampton Wanderers side on Boxing Day that have conceded 40 times in 17 Premier League games.
Furthermore, United will travel to Molineux with the joint-best defensive away record in the division, conceding only eight goals in as many games.
