Joleon Lescott believes Ruben Dias has quickly proved himself to be "the guy" in the Manchester City defence.
The Portugal centre-back was brought in for a club-record £64.3million last summer to address one of the main areas of weakness in Pep Guardiola's side.
His impact has been immediate with a much more defensively resilient City emerging as strong Premier League title favourites.
With Dias in the side, City have kept clean sheets in 12 of their last 14 Premier League games and won nine in a row to move to the top of the table.
Former City defender Lescott, a member of the title-winning sides of 2012 and 2014, said: "He's had a massive impact.
"The biggest thing for me is his reliability and consistency. He's solid at all aspects – heading, tackling – but his availability is the biggest thing. He's played 50 games in the past two seasons with Benfica and already played 27 for City.
"That's a huge thing, having someone who is always fit and available. He has come in and been the guy."
Dias has quickly built a strong partnership with John Stones, who has rejuvenated his career playing alongside the newcomer while Aymeric Laporte has been out injured.
Lescott can see similarities with his own successful partnership with Vincent Kompany.
"Vinny needed a partner," Lescott said. "He needed someone who allowed him to do what he was good at. I recognised that and I think John Stones has recognised that (with Dias).
"When I saw him play with (Nicolas) Otamendi, they were almost playing against each other – playing alongside each other but competing to be in the team.
"Now John Stones is looking to complement someone. That will help Laporte as well because I think he's realised Dias is that guy."
Lescott claims Dias has been so good that he has hardly needed to use his pace.
"The pace surprised me," said Lescott, 38, who is now retired and has a role with City managing players out on loan as well as working as a media pundit.
"The best compliment I can pay him is he's played 27 games and I've only just realised he's super quick. I love that.
"A lot of defenders you can watch, and you know after 10 minutes he's quick because he's in the wrong position and he's had to use his pace to get out of trouble.
"I've only noticed it once with Ruben Dias and that's it. That's because he is in the right position all the time."