And the Ajax star was happy to oblige on behalf of the team he will join in the summer - and the Dutch club's jubilant army of supporters.
“I spoke to them when I signed the contract and they told me to try to knock out Real Madrid, as that would be great for Barca too,” De Jong told Dutch newspaper De Telegraaf before Tuesday night's stunning 4-1 victory over Real at the Santiago Bernabeu .
De Jong, who will move from Ajax to Barca for €75 million (£65m/$85m) in the summer, reportedly spoke to a delighted Bartomeu again after the win which gave the Dutch team a 5-3 aggregate passage to the quarter-finals.
Describing how helping out his future employers felt, De Jong - one of the stars of a superb performance from the Amsterdam club - told Veronica TV : "Cool, but I'm mostly happy for Ajax and the fans.
"It is amazing to beat Real Madrid with these numbers, especially at Bernabeu. People might have expected something from us, but not in this fantastic manner.
"In the first game it wasn't much worse than this, but back then we were unlucky with the score. Now, everything worked out perfectly for us."
De Jong does not care who Ajax get in the next round, adding: "Each opponent will be tough. We'll be the underdogs, but that's nothing new. We're happy to march on, very, very happy."
It was not all plain sailing for the 21-year-old midfielder, who suffered from cramp in the latter stages of the game - and almost cost his side.
"I played a decent game, but in the end the game almost got tricky again because of me," he added. "I shouldn't have lost that ball there, but I had cramps in both legs.
"On a night like this that error luckily wasn't punished."
Ajax won with goals from Hakim Ziyech, David Neres, Dusan Tadic and Lasse Schone, with Marco Asensio grabbing Real's solitary goal, as their season descended into further turmoil following the Copa del Rey exit at the hands of Barcelona last week and Clasico defeat in La Liga against their arch-rivals.