Manchester City manager Manuel Pellegrini reckons Sergio Aguero has it in him to become an even better player despite the striker's superlative start to this season.

Aguero has scored 11 goals in as many games so far this term, including four for the Premier League champions in their victory over Tottenham Hotspur last weekend.

Injuries hampered Aguero throughout the latter half of last season and he did not appear to have recovered completely by the time he represented Argentina at the World Cup in Brazil.

However, the 26-year-old appears to be firing on all cylinders now, although Pellegrini said Friday he had still to reach his peak.

"Sergio is a young player, he has a lot of years to improve -- three or four years more than other players," Pellegrini said.

"It just depends on what he wants to do in the future. I think he has all the conditions to do that," the Chilean added.

"I don't think it is the best I have seen from Sergio. I was always sure he would return to his normal performance but I think he can get even better."

City, second in the table ahead of this weekend's matches, have also been indebted of late to the form of Frank Lampard, who joined on loan from US sister club New York City FC.

However, the former Chelsea and England midfielder will miss Saturday's match away to another of his former clubs, West Ham, after sustaining a thigh injury during the 4-1 win over Spurs.

"Frank is not ready for this week but maybe I think next week he will start working with the whole squad," Pellegrini said. "It will be a short injury, less than we thought at the beginning."

Such has been Lampard's impact, there have been reports City could extend the 36-year-old's loan even though he is due to link up with New York early in the new year to prepare for the 2015 Major League Soccer season.

Lampard may be able to satisfy both clubs should New York, as has been suggested, hold a pre-season training camp in Manchester but a non-committal Pellegrini said: "One thing is not related to the other thing.

"Maybe New York City can work here in January but that is not depending on the future of Frank Lampard.

"We will see what is the future of Frank. For the moment he is here in Manchester City."

Second-placed City's trip to Upton Park gives them a chance to reduce leaders Chelsea's five-point lead at the top of the table before the Blues face Manchester United at Old Trafford on Sunday.

Pellegrini's men beat West Ham four times last season, scoring 14 goals, but the Hammers are a transformed team this term and are currently fourth in the table.

"West Ham are in a good moment, playing good, attractive football," said Pellegrini. "They are scoring a lot of goals, they had an important win against Liverpool at home and they have won their last two games."

For City, their match in east London represents a chance to end a frustrating week on a high following a controversial 2-2 draw away to CSKA Moscow that dented their hopes of qualifying for the knockout stages of the Champions League.

City conceded a disputed late penalty in a 2-2 draw while there was further tension off the field when it appeared some 30 CSKA fans were in the ground despite the match being designated a "behind closed doors" fixture as punishment for racist incidents involving the Russian club's supporters.

"I don't want to link both things - the result and what happened with the fans," Pellegrini said. "I think the only punishment was (for) our fans because they couldn't go.

"Of course it was a frustration, we lost two important points. But in the Champions League the most important thing is to qualify for the next stage, so you can make a mistake.

"Where we cannot lose points is in the Premier League. Now all of us are thinking about West Ham."