Once at PSV, he was re-schooled as a defender, using his aggressiveness to charge up and down the sideline, and following a first season of few matches, he commanded the left back position in his second year, and made it his own.

Heintze returned to finish his career at PSV in 1999, with his old team mate Eric Gerets the head coach.

Approaching 40, Heintze was looking to help the young Wilfred Bouma into the team as new left back, while using his experience to provide stability in the defense.

Following the international retirement of Peter Schmeichel in April 2001, Heintze captained his country at the 2002 FIFA World Cup, under new Denmark coach Morten Olsen.

In a Euro 2000 qualifying match against Belarus on 5 June 1999 he scored a memorable goal, directly from a corner kick.