Manuel Pellegrini admitted he was at a loss to explain Manchester City's 3-2 defeat at Aston Villa.
City twice took the lead at Villa Park, through Yaya Toure and Edin Dzeko, who scored either side of Karim El Ahmadi equaliser, but ended up suffering their second 3-2 away reverse this season.
Leandro Bacuna levelled the game with a precise free-kick before Andreas Weimann capitalised on uncertainty at the back post to poke past Joe Hart and seal a surprise win for Paul Lambert's side.
And Pellegrini said it was "unbelievable" that his side couldn't make it back-to-back Premier League wins.
"Of course it is disappointing because I think we played very well in this game," he said.
"From the beginning we had possession of the ball, we had the chances and we didn't have any risk in our own goals.
"It is unbelievable we didn't win this match but football has these things. The team that deserves to doesn't always win."
City are yet to win away from home this season, losing 3-2 at newly promoted Cardiff and picking up their sole point at Stoke.
Pellegrini said: "I think the first goal was offside, the second goal was a free-kick and the third goal was unbelievable.
"Maybe drawing 2-2, at that moment, made the players go forward and we left a gap. They had the ball with the goalkeeper and then a chance to score in our goal.
"In five minutes we threw away all the work we did in the whole match. For the moment we haven't had a victory away. The other two games were very different, against Cardiff and Stoke. I thought the team played the way we need to play and the way I want to play there. I can't believe we didn't win."
But Pellegrini has no doubt City will recover to play a prominent role in the title race.
He added: "We are not thinking about the title at the moment. We are thinking about winning the most amount of matches.
"In the Premier League, the difference [between teams] is very small. If we play the way we are playing I am absolutely sure we are going to be fighting for the league."
Even though his team were outplayed for most of the first half, Villa boss Paul Lambert had no doubt they could fight back.
He said: "I know they had a lot of possession but Guzan didn't really have a save, as such. They are one of the favourites to win the Premier League, and one of the teams that could win the Champions League.
"That shows the magnitude of this result. They might have rested a few for the Bayern game but, if you look at the side, there were a lot of top players. It is a big win, three points for us. I am delighted to win."