Cody Gakpo twice slipped Isak in behind to score inside the opening 10 minutes on a routine night for Andoni Iraola's team.
That moves Isak onto three goals so far this campaign with Gakpo on three assists as Iraola's attack begins to take shape after back-to-back draws at the start of the season.
New signing Bradley Barcola was given a 25-minute cameo off the bench in place of Victor Munoz and Iraola was pleased with how the Frenchman performed - despite a limited preseason at PSG.
"I was tempted to start Barcola. He's looked good in training, but hasn't played a minute in preseason.
"I think he's ready, but we have to be cautious as we don't want to lose him straight away.
"I think he had some good minutes. I think he has a very good pass.
"In a counter, a couple of times we didn't find him, so we have to learn these kinds of movements because he'll be in behind, threatening all the time.
"He hasn't played any competitive minutes since the World Cup, so we have to be a little bit more careful, but he's been very good."