Celtic went into half-time two apiece with the Croatian side but conceded twice in quick succession as they ended their group-stage in disappointment.
And Johansen, despite qualification already being sealed, was particularly frustrated with the Hoops' display.
"It’s not good enough," the Celtic midfielder told reporters. "At least we’re through. But we need to do much better than this if we’re going to go through the next round. It wasn’t our best game and while I’m happy we’re through we must be much better in the knockout stage.
"I don’t think the performance had anything to do with the fact we were already through. We all looked sharp before the game and we just shouldn’t concede four goals in the manner we did."
Van Dijk, however, was far more relaxed...
Yes, the Dutchman admitted his side were poor defensively - but the 23-year-old says the Hoops should not be 'too concerned.'
"We need to learn from this and move on," he said. "But I don’t think there is any need to be too concerned. We showed already we can be compact and press well.
"As a team, we need to stay compact. We need to work on that and we already are. I think it’s better than it was at the start of the season."