Tomasz Kuszczak had been tipped to step in for his first Premier League start of the season after he kept a clean sheet in the Carling Cup win over Wolves.
However, Ferguson has been quick to give Foster a public vote of confidence, saying: "It was a good opportunity for Tomasz to play on Wednesday but Ben will play on Saturday. Ben has not had a lot of game experience but he will be OK."
Meanwhile, Ferguson confirmed he expects first-choice goalkeeper Edwin van der Sar to be out for another three weeks.
The veteran Dutchman suffered two broken fingers in a pre-season game against Bayern Munich in July and was immediately consigned to a couple of months on the sidelines.
Now Ferguson has revealed he does not expect Van der Sar to be back in action until after the next international break.
"We still feel he is three weeks away," confirmed the United boss, who reported no new injuries following his side's last two games.