Alderweireld enjoyed a stunning 2015-16 season with Tottenham and was one of the best defenders in the Premier League.
The 27-year-old is a key figure in the Belgium squad currently on international duty at the ongoing 2016 European Championship in France.
Belgium have reached the quarter-finals of the prestigious competition and will face Wales for a place in the last four.
Looking ahead to the game on Friday evening, Matthaus suggested in The Sun that Alderweireld is not as good as some of the other defenders at the Euro 2016 finals.
The former Germany star seems to believe that new Bayern signing Mats Hummels (Germany), Jerome Boateng (Bayern and Germany) and Giorgio Chiellini (Juventus and Italy) are better defenders than Alderweireld.
“Wales can exploit Belgium's problems at the back,” Matthaus wrote in The Sun. “While Toby Alderweireld had a very good season for Tottenham, he is not a Hummels, Boateng or Chiellini.
“And now it will be even tougher for them with Thomas Vermaelen suspended and Jan Vertonghen crocked. Wales will see Jordan Lukaku as somebody they can exploit.”
Alderweireld has scored one goal and created one chance in four matches for Belgium at the ongoing 2016 European Championship in France so far.
The Tottenham defender has pass accuracy of 87% and a shot accuracy of 40%, and has won five headers and three tackles.