Manchester City striker Sergio Aguero can become the best player in the world, according to Manuel Pellegrini.
Aguero goes to West Ham on Saturday on the back of his four goals against Tottenham last week - a haul which strengthened his position as the man with the most goals-per-minute in Premier League history.
And while much of the world debates the respective merits of Cristiano Ronaldo and Lionel Messi ahead of Saturday's Sky live Clasico in Madrid, Pellegrini is convinced his 26-year-old striker - now fit after an injury-hit season last year - can eventually match them both.
He said: "I think he has all the conditions to do that.
"Sergio is a young player, he has a lot of years to improve - three or four years more than other players. It just depends on what he wants to do in the future.
"I was always sure he would return to his normal performance but I think he can get even better."
Containing Aguero is the immediate concern of West Ham, but Pellegrini expects the league's fourth-placed team to carry a big threat of their own in East London.
He said: "West Ham are in a good moment, playing good, attractive football. They are scoring a lot of goals, they had an important win against Liverpool at home (last month) and they have won their last two games.
"I am sure we are going to have a very difficult rival, exactly as we have every game in the Premier League."
Frank Lampard is expected to resume training next week but will again be missing having sat out the midweek trip to CSKA Moscow.
City drew 2-2 in Moscow, a result partly overshadowed by a row over several hundred spectators who attended the game despite its behind-closed-doors status.
Pellegrini said: "I don't want to link both things - the result and what happened with the fans. I think the only punishment was for our fans because they couldn't go.
"For me, it is more important to talk about football, not to talk about rules or punishment, it is not my duty."