The Tottenham Hotspur winger has been discussing his new team-mate.
And the winger also feels his fellow Belgian can provide the missing piece of the north London side's jigsaw - as he can bring 'calm' and 'consistency' to Mauricio Pochettino's defence.
The White Hart Lane outfit struggled badly at the back last term and have, as such, strengthened majorly in defence this summer, recruiting Alderweireld, Kevin Wimmer and Kieran Trippier.
Chadli told Tottenham's official site: "Jan and Toby played a lot of games together at Ajax so they know each other very well and I think they’ll be very comfortable playing alongside each other.
"Toby has settled in very nicely this week, the lads have welcomed him and he knows us very well so I think, for him, it’s all good.
"I believe he can bring a lot of calm to our defence as he’s somebody who can play with consistency. He always plays a good game and he’s honestly a good lad in the group - very calm and respectful. I think he’s a great addition to the squad."
Could Alderweireld, then, finally provide the key to solving Tottenham's biggest problem last season?
As Opta stats show, Spurs conceded the joint-fifth worst number of goals in the Premier League last campaign. In other words, based on their defence alone, the north London side were on par with relegated side Burnley and would have been in a relegation dogfight - not fighting for fifth or above.
Part of Tottenham's problem, of course, was a lack of support from midfield. But that's another area Alderweireld can assist with, as the Belgian is able to play as a defensive midfielder.
The 26-year-old should also help get the best out of Vertonghen, who was well below par last season based on his normally high standards.