The former Netherlands international is hoping that his former side will bag the full three points on Sunday as he is still closely monitoring their performances
The combative midfielder left San Siro for PSV in the summer transfer window after an 18-month spell at the Serie A giants, but the Dutchman has not forgotten about his former team just yet.
"There's no doubt about it that I will be rooting for Milan in Sunday's derby," he told reporters.
"It is an important match and even more important as Milan have to make up for the points they lost earlier this season. It will be a great game.
"I still think about Milan a lot. I have regular contact with a number of the players and I talk to the people at Milanello occasionally.
"They had a difficult start to the season and lost a lot of quality. They also signed some quality players, though. I am confident that they will get back on track and climb in the league table."
Sunday's Derby della Madonnina kicks off at 20:45CET.