The defending Premier League champions crashed out of the competition at the fourth-round stage after Sky Bet Championship side Boro pulled off a shock 2-0 win at the Etihad.
It was City???s second home defeat in a row and raised further questions about the wisdom of returning from their warm-weather training camp in Abu Dhabi less than 24 hours before the game.
While Pellegrini denied travel was a factor in City’s disappointing display, he??admitted his side???s form is a worry ahead of their??crunch Premier League clash with Chelsea next Saturday evening.
???I am concerned, not because of the Chelsea game, but because in the last two games here at home we didn’t score goals and because in the last (five) games here at home we conceded two goals in (four of them),??? he said.
“Maybe in one week we threw to the trash all we did in December. We need to try to recover our performance in attack and in defence.”
Following their shock FA Cup defeat on Saturday, City are now??without a win in three matches and have not kept a clean sheet in seven.
But a win over Chelsea would help alleviate??some of the pressure on Pellegrini and he says he is already looking ahead to the crucial encounter.
???I am going to start working on that game,” he commented. “We don’t have any problem with motivation. I think we are going to work hard and I hope we can win that game at Stamford Bridge.”