Toure has so far failed to replicate the form which saw him score 24 goals from midfield in all competitions last season after a summer in which he lost his brother Ibrahim to cancer.
But the Ivory Coast international scored the opening goal in City's 2-0 win over Aston Villa earlier this month and Pellegrini believes his star man is slowly returning to his best form.
"Yaya has the quality to make a difference. He had a difficult summer but every game he is getting better," he told reporters.
City will take on CSKA Moscow on Tuesday evening in a closed Arena Khimki as the Russian Premier League leaders begin a three-match sanction in European competition due to the repeated racist behaviour of their supporters.
CSKA star Ahmed Musa described the ban earlier this week as "unfair", and Pellegrini admits the situation is far from ideal.
"It is a pity we cant play for fans, as this competition is for the fans," he added. "But we dont have any other option."