Manuel Pellegrini, the Manchester City manager, believes Sergio Aguero has the potential to become the best player in the world.

The City striker has made a superb start to the campaign - scoring 11 goals in as many games, including four against Tottenham Hotspur last weekend.

That ratio has renewed debate over the Argentine's standing in the game. A year ago, for example, comparisons were often made between Aguero and the likes of Cristiano Ronaldo and Lionel Messi, only for injuries to then hamper Aguero throughout the second half of last season.

Those fitness problems, which also appeared to affect the Argentina internationalist at the World Cup, now seem behind him and he appears close to his blistering best once more. However, Pellegrini expects the 26-year-old to improve further and eventually surpass his more celebrated contemporaries.

"Sergio is a young player, he has a lot of years to improve - three or four years more than other players," said the City manager, whose side face West Ham United this afternoon. "It just depends on what he wants to do in the future. I think he has all the conditions to do that.

"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's trip to Upton Park gives them a chance to cut Chelsea's five-point lead at the top of the Barclays Premier League and put pressure on Jose Mourinho's men, before they take on Manchester United at Old Trafford tomorrow.

City defeated West Ham four times last season - scoring 14 goals along the way - although Pellegrini has insisted that counts for little and has noted the fourth-place London club's impressive start this term.

"West Ham are in a good moment, playing good, attractive football," added the City manager.

"They are scoring a lot of goals, they had an important win against Liverpool at home and they have won their last two games. I am sure we are going to have a very difficult rival."