Foden had given City the lead after 15 minutes, tapping home Joao Cancelo's cross into an empty net, before an unfortunate own-goal from John Stones brought the Belgian side level just two minutes later.
It wasn't until the second half when City managed to break through the spirited visitors, when Riyad Mahrez headed past Simon Mignolet, before Raheem Sterling and Gabriel Jesus added a third and fourth respectively.
"I thought we had a sloppy first half, we let them get back into the game," he said.
"We got in at half-time, spoke about what is going wrong and in the second half, we played much better.
"I don’t know what it was, we looked a bit heavy, like we didn’t have energy.
"The manager wasn’t happy. You have to take his advice.
"He changed a couple of things in the second half and I think we were much better in possession, we hurt them in behind a lot more with the space.
"Once we get the rhythm and play our lovely football, chances start opening up and I was delighted with the second half."
Foden started the game in the number nine role and repaid the manager's choice with a goal, but the City youngster is now looking for a strong finish to the group stages.
"I’m scoring a lot of goals, playing in the nine role now is something new for me and I am just enjoying it," he explained.
"It was a really important win today. It puts us in a good situation and we want to finish strong now against PSG."