Manchester City manager Manuel Pellegrini got his calculations wrong on Chelsea's spending during the January transfer window, according to Blues boss Jose Mourinho.
Mourinho described his team as a "little horse" in the Premier League title race, while Pellegrini said Chelsea were a "rich little horse".
"Mata was sold for £37m and De Bruyne for £18m - that's £55m," said Mourinho.
"Matic bought for £21m and Salah £11m. In this window, we are plus £23m."
Mourinho added: "We are building a team for the next decade and City have a team to win now.
"They have experience, potential, power and no worries about [Uefa cost control protocol] Financial Fair Play, because in summer they just spent. We don't need a calculator for this."
Chelsea lead the Premier League by a point following Saturday's 3-0 win over Newcastle. Arsenal are second and City third, two points behind Chelsea.
Mourinho has played down Chelsea's title chances in recent weeks and on Saturday, he described City as "a Jaguar" and said they are favourites for the title. He added that his concern was the gap between Chelsea and fifth place.
Former Malaga boss Pellegrini, who faced the Portuguese when Mourinho was coach of Real Madrid, questioned Mourinho's view and drew reference to Chelsea's spending over the last decade, since Russian billionaire Roman Abramovich bought the club.
The Chilean said last week: "Maybe it is a small horse if the manager thinks like that.
"It can be a little horse but very rich. This is the team that spends most money in the last 10 years, it is the team that spends most money this year and the team that spends the most money in the transfer window, so [it is a] little bit rich."
Chelsea's net spend during the previous two summer and winter transfer windows was approximately £49m.
In January, they bought Nemanja Matic, Mohamed Salah and a player Mourinho did not mention, Kurt Zouma (£12m), for a total of £44m. But they made £55m from the sales of Juan Mata and Kevin de Bruyne.
City, on the other hand, did not change their squad during the winter window, but had a net spend of about £80m last summer.
Mourinho said of Pellegrini: "He has been speaking about winning four competitions, so there's no reason to change the speech.
"But the only thing that is funny [is] that he keeps saying he never responds to Mourinho; he never comments about Mourinho. He said that in Spain, too. So he's changed."
Chelsea travel to West Brom on Tuesday and Manchester City host Sunderland on Wednesday.