Manuel Pellegrini says Sergio Aguero is as important to Manchester City as Lionel Messi and Cristiano Ronaldo are to their clubs.
Aguero continued his brilliant form with a hat-trick in the 3-2 Champions League win over Bayern Munich on Tuesday and the City boss is convinced there is even more to come from the Argentina striker.
He already has 17 goals this season, leading to further comparisons with Barcelona star Messi and Real Madrid's Ronaldo, and Pellegrini thinks he is worthy of being in the same conversation with the world's best two players.
"Well of course I think that no one can replace Messi at Barcelona, Ronaldo at Real Madrid or Sergio here - or a lot of very important players. It is not the same playing without Aguero as with Aguero," Pellegrini said.
"He has many years more to play here. I am always asking and demanding that he tries to be the best player because he has all the conditions to do that.
"That is why I am very glad for him he is always improving every day.
"I think he is a top player, a very important striker here in the Premier League and we are very glad to have him in our team."
If he plays, Sunday's clash with Southampton will be his 100th Premier League appearance and only Alan Shearer (79) and Ruud van Nistelrooy (68) have more goals after 99 games than Aguero, who has 64.
He was allowed to play himself into the season, after injury hampered him towards the end of last season and during the World Cup, and Pellegrini feels City are seeing the benefit of that now.
"You never know when a player will be injured but I think that this year we prepared him in the correct way," he said.
"If you remember in the first three games, including the Community Shield, we didn't play with Sergio, we just gave him 20-25 minutes, no more, so he could have a good pre-season. He needed that after the last season when he had a lot of injuries.
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"He is fit and we hope he will continue in this way until the end of the season. I always say we have a squad and if, for different reasons, Sergio cannot play, we must have another one that can do it.
"We hope he continues the same way but I suppose Edin Dzeko will be fit next week and he can score also. Atr this team we never depend just on one striker.
"The last league game, Sergio didn't score and we won with a goal from Stevan Jovetic and one from Yaya Toure. If you remember, we won the title here last year with a lot of games without Sergio. But, when he plays, it makes a difference."
Watch Southampton's Premier League clash with Manchester City live on Sky Sports 1 on Sunday - coverage starts at 12:30pm.