Manuel Pellegrini is confident Manchester City will see Yaya Toure back to his best after insisting the problems the player faced last season are now behind him.
Toure was on the scoresheet as City showed their Premier League title credentials with an impressive 3-0 opening-game win away to West Bromwich Albion on Monday.
Having seen rivals Chelsea and Arsenal both slip up over the weekend, City manager Pellegrini's team took full advantage with a dominant display which will give them confidence ahead of Sunday's showdown with Jose Mourinho's champions.
Having struggled to find his best form for a variety of reasons last term, the performance of Ivory Coast star Toure stood out as he gave signs he is fit and focused with a dominant display at the heart of City's midfield.
"I always said last season it was a strange season for Yaya, he started with a lot of problems, the death of his brother, his agents, I think he was not focused maybe on what he had to do last year," Pellegrini explained.
"We spoke a long way before the start of the season and I am very sure we will see the Yaya from two years ago. He is a very important player for us," the Chilean added.
"I don't think Yaya deserved the amount of criticism he received last season. It was not his best season but he did not play so, so bad like everyone said.
"But he is an important player for us. I am sure last season his head was not in his best moment. It is very difficult for a player when you have so many problems."
Toure and David Silva combined to hand City the initiative just nine minutes in, with the Spain international flicking home his teammate's shot with the aid of a deflection before midfielder Toure curled home a fine second goal 15 minutes later.
With Vincent Kompany making the points certain, City's old guard overshadowed STG49 million record-signing Raheem Sterling on his competitive debut.
The former Liverpool forward twice had good opportunities to join them on the scoresheet only to be foiled from close range by Baggies goalkeeper Boaz Myhill.
"I'm not disappointed because Raheem plays 70 minutes very well (before he was substituted)," said Pellegrini. "If he continues to play like this I am sure he will be the player we bought."
West Brom boss Tony Pulis refused to blame his players for the defeat. "I take responsibility for the way we set up and the fact we had (two strikers) Saido Berahino and Rickie Lambert both playing," said Pulis.
"I have to look at it and say if I did it again I would probably do it differently. The pivotal moment was when I decided to play the two up front instead of an extra man in midfield."