West Bromwich Albion are currently six points clear of the drop zone.
The Baggies looked in little danger of relegation, but a poor run of form has dragged them back towards the bottom three.
West Brom were beaten by relegation-threatened Newcastle United in their most recent fixture, and Foster has warned his teammates that they are not clear of danger yet.
“I think we need three or four more wins to get us safe and that will be about it,” Foster said.
“Fair play to the following support that came and got behind us but we were a bit short.”
West Brom have now failed to win any of their last five Premier League matches, and they also could only pick up a draw against Peterborough United in the FA Cup.
The Midlands side have struggled for goals recently, and even their previously solid defence has started to show signs of weakness.
West Brom’s poor sequence of results has raised the pressure on Pulis, with his side now only six points above the drop zone.
The Baggies’ next fixture comes against Peterborough in the FA Cup tomorrow, before they take on Everton in the Premier League at the weekend.