Aguero, who has scored 26 times this season, was forced off at half-time in the Nou Camp on Wednesday as City slumped to a 2-1 defeat that confirmed their exit from the Champions League.

He has undergone a scan and although City are still waiting for results to assess the severity of the problem, Pellegrini on Friday admitted Aguero will definitely miss the trip to the KC Stadium.

Pellegrini is hopeful Aguero, who missed five games with a hamstring injury in February, will be back within a fortnight, although a two-week absence would see him miss the derby against Manchester United on March 25.

"I really don't know, but I don't think it is really very serious," Pellegrini said.

"I am hopeful he will (only) be injured for a couple of weeks."

Aguero's absence is a major blow to City's hopes of winning the Premier League title.

Fourth placed City trail leaders Chelsea by nine points, although they have three games in hand.

After winning the League Cup final two weeks ago, City have crashed out of the Champions League and FA Cup within the space of a few days.

With their dreams of a quadruple over, Pellegrini must work to restore his players' morale in time to revive their title challenge.

"I hope that City will recover the performances that we played until one month ago," he said.

"I think in the last month we felt a little bit the 18 games that we played in two months -- that is the cost of being in all the competitions.

"I always want to stay in every competition, in the Champions League and FA Cup.

"But if you continue in it, it is more difficult. The amount of games in the last month has been very high.

"This is the only positive thing from going out -- we can focus absolutely on the Premier League.

"That is why it is so important to win on Saturday because then we will have same as Liverpool and Arsenal, a week to prepare for every match.

"We need to win all the games from now until the end of the season.

"It is the moment to recover, to see our mentality and I hope we are going to do a very good game against Hull and get three points."