Louis van Gaal's Manchester United got an important week off to a "very bad" start after Juan Mata's red card helped West Brom to victory.
The doom and gloom around Old Trafford was lifted somewhat after a run of four successive wins in all competitions - an upturn in fortunes halted at The Hawthorns as Solomon Rondon secured Albion a 1-0 win.
Mata's first-ever red card for two bookings in less than three first-half minutes was key to the visitors' downfall, with Van Gaal calling it the "turning point" in yesterday's Barclays Premier League encounter.
The Dutchman is hoping the disappointment does not negatively affect United going forwards, especially as this week sees a Europa League trip to Liverpool followed by an FA Cup quarter-final against West Ham.
''I think always this match has an influence on the next match so it is, for us, very bad," Van Gaal said. ''It is a bad moment and it wasn't in my opinion a necessary loss.
"I don't want to say that we deserved to win, no, but we don't deserve to lose.
"When you see at the end the chances that West Bromwich Albion has created in comparison with us, it was an unnecessary loss.
"When it is a draw and you play 60 minutes with 10 men, you can accept it - but now you lose and you lose contact with the first four or five."
United end the weekend sixth in the Barclays Premier League, three points behind fourth-placed Manchester City.
Manuel Pellegrini's men also have a game in hand and Van Gaal believes things would have been different had Mata not been sent off.
The Dutchman told broadcasters the first booking was "stupid" but suggested referee Mike Dean should have taken the Spaniard's character into consideration before brandishing a quickfire second.
''My opinion doesn't count,'' Van Gaal said when asked about Mata's red card.
"You give as a referee within five minutes two yellow cards to the same person and you know also who Juan Mata is.
"I asked him a rhetorical question: 'How many red cards (have you had in your career)?' None (he said). I had assumed that already.
"(But) as a player you have to know also when you have a yellow card that you have to take care of that."
It was Albion's first league win at home to United since March 1984 and, more importantly, almost certainly secures their top-flight status.
The Baggies now sit on 39 points and, having jokingly dismissed captain Darren Fletcher's target of 50 as ''nonsense'', head coach Tony Pulis is focused on reaching the 40-point mark.
"Let's get to 40 and then take it from there," the West Brom head coach said. ''I think 40 points is always (required).
"It is very difficult managing teams in the lower half of the Premiership. It is really, really hard work mentally and physically."
