Tottenham Hotspur meet Southampton at the weekend.
Alderweireld was on loan at Southampton last season and he says that the south coast club have developed something special.
The Belgian defender was very impressed by the squad Ronald Koeman assembled at St. Mary’s, with Graziano Pelle, Sadio Mane, Victor Wanyama and Dusan Tadic earning particular praise.
“They have a very decent team and have played well this season,” Alderweireld said.
“If you look player by player, it’s a strong squad. They are consistent and capable of beating anyone and they have something special there. Graziano Pelle is a good player, Sadio Mane, Victor Wanyama, Dusan Tadic and I could keep going.”
Southampton had wanted to make Alderweireld’s transfer from Atletico Madrid a permanent one in the summer transfer window, but the centre-back opted to move to White Hart Lane instead.
Southampton have missed Alderweireld and in his absence their form this season has not been as impressive.
Spurs, meanwhile, have made an excellent start with Alderweireld at the heart of their defence.
The Lilywhites are lurking just outside the Champions League qualification spaces, and they could move into the top four if they are able to beat Southampton at the weekend.