The Bayern Munich boss thinks the Blues caretaker manager deserves to be given the role permanently by Roman Abramovich, even if they lose in the Champions League final
The two men will go head-to-head for Europe’s top football prize at the Allianz Arena, but the game could be Di Matteo’s last in charge with owner Roman Abramovich believed to be ready to recruit again.
But Heynckes believes that, regardless of the result, Chelsea should make Di Matteo its full-time manager for turning around what looked like a disastrous season under former boss Andre Villa-Boas.
"We must not forget that he has brought Chelsea all the way to the final with a very calm attitude,” Heynckes told reporters.
"It seems he's a very cool person who's very much in control. Step by step, he's improved contact with the players and created harmony. That harmony can be felt.
"He's done a marvellous job and I can't see why whether he wins tomorrow or not would have consequences. You need continuity.
"I don't think there's any argument against him continuing."
If Di Matteo lifts the Champions League trophy on Saturday and is sacked by Abramovich, he would become only the second manager to lose his job immediately after winning the competition.
Ironically, Heynckes was the first manager to do so, after leaving Real Madrid following European success back in 1998.
And, though he understands why the Chelsea owner could seek a more decorated manager, Heynckes says he would carry on with the current interim manager.
He added: "He makes an excellent impression on me and, if I was Abramovich, I would continue with this young man."