The 33-year-old is better placed than most to carry that belief having played for the Govan club between 2013 and 2015, and spending time on loan with the Gers earlier in his career.
The Light Blues will be buoyed by the 2-2 draw with Villarreal in their Europa League group stage opener in Spain on Thursday night but Foster believes there will be no let-up in expectations of the home crowd on their return.
"As a home player you have to win," said the former Aberdeen and Ross County player.
"It doesn't matter if you play well, you draw the game it is not good enough. You have to win the game.
"The fans want you to play well and win the game of course but sometimes you just need to dig in and get the result.
"Whereas there is less pressure on the away team. No one expects us to go there and win.
"If you can keep Rangers quiet for 15 to 20 minutes the crowd maybe start to turn and maybe grumble a bit.
"You can hear it and it does have an affect so hopefully that's what we can do, go there and frustrate them."
Saints have lost only once in 10 games in all competitions this season – 2-0 at Kilmarnock on the opening day of the Ladbrokes Premiership campaign.
Foster knows the Perth side will have to have to hit peak performance level if that good run is to continue.
He said: "Ibrox is a tough place to go. Rangers are a good side so you need to be at the top of your game to beat them.
"We showed that last year when we went there and won 3-1. We showed that we can do it.
"It was up there with our best performance of the season.
"To a man we did our job very well. There is no telling how we are going to play but if we reach that level of performance we will give ourselves a right good chance to win the game.
"This year, we have a bit more pace in the team going forward.
"Rangers are going to have most of the ball, we know that, but we can be dangerous on the counter attack."