City need four wins from their final four games to be sure of retaining their league title, and must see off their great rivals on their own patch in order to keep their destiny in their own hands.
Liverpool are two points ahead of City but have three league games remaining, while the defending champions have four.
“I’m just happy to help the team and get the win,” said Foden.
“It hasn’t really sunk in yet [to have scored the winner]. I’m just happy to get the win and help the team. It could be [a big goal], we’ve still got four difficult games left and we need to win them all. We need to keep going.
“I can’t see Liverpool dropping points, we need to win them all.”
United host City on Wednesday night, and anything less than a win for the visitors will mean Liverpool will assume the position of favourites in this tensest of title run-ins with three games to go.
City missed the opportunity to clinch the title against their biggest rivals last season, when they let slip a 2-0 lead to lose 3-2 at the Etihad when a single point would have wrapped up the league.
“It’s a very difficult game, to go to United, and play well,” said Foden. “But I know we are capable of doing it. If we win this one, we are a step closer. So let’s see what happens. And I’m confident.
“This morning, before the game. It was a bit of a surprise but I was always ready to take my opportunity.
“Any game I’m going to play in, I’m going to be excited
“That’s picked us up a bit from the other day, we are ready to go and we are feeling confident with smiles on our faces. We know we can do it.
“When we won the league and we were miles in front, I think this will be better because we’ve actually had a challenge and someone fighting with us. If we do this then people have got to start telling us we are one of the best teams.”