Tielemans answered Italian media's questions about stepping up under manager Unai Emery after Luiz left the club and how he and fellow Belgium international Amadou Onana have transformed Villa’s midfield.
When Luiz left for Turin many questioned the move and now all but one of his eight appearances so far for Juve have been as a substitute. He has even given away penalties in consecutive matches against RB Leipzig and Cagliari.
Tielemans has since defended his friend and former teammate and says that despite his slow start Diaz will get to grips with Italy.
"Douglas is a very technical player, he was very important for us," the 27-year-old replied to the Italian media who have been harsh on Luiz and his performances so far this season.
"He decided to leave in the summer. But all I can say is that he is a player of great quality, he works hard and by working his quality will emerge to light."