Chelsea and Spurs face off on Saturday, with Mourinho and Tottenham boss Andre Villas-Boas set to go head-to-head.
They worked together at Stamford Bridge, but there's no love lost between the pair.
Still, Mourinho has praised Villas-Boas for his work in the transfer window, crowning the north London club "champions" after a busy summer of dealing.
"They are the champions of the transfer market," Mourinho was reported as saying in the Daily Star.
"You win titles with squads, not with an especially good player, so Tottenham are bigger contenders than before."
Spurs sold Gareth Bale in a world record £85m deal towards the end of the summer window, but not before they spent lavishly upgrading their squad.
Villas-Boas brought in Erik Lamela from Roma, Paulinho from Corinthians, Danish international Christian Eriksen, Etienne Capoue from Toulouse and Roberto Soldado, formerly of Valencia, among others.
The influx was largely paid for by the sale of Bale to the Bernabeu, and the new Spurs stars have quickly adapted to life at White Hart Lane.
Injury to Capoue means the Frenchman will not feature against Chelsea on Saturday afternoon, but Soldado and Eriksen should start after they were rested in the mid-week Capital One Cup victory over Aston Villa.