Having scored just three points since the summer break, Vijay Mallya admits Force India face a "real fight" in keeping Sauber at bay.
Force India made a flying start to this year's Championship and were even ahead of McLaren in the Constructors' Championship before Pirelli changed the compound of their tyres.
That resulted in a massive slump for Force India, who have netted just one top-ten grid position and only three points in the ensuing races.
"The races after the summer break haven't been very positive in terms of scoring points, but the morale in the team remains strong," Mallya said.
"Korea and Japan were not the easiest of weekends, but everyone in the team is working really hard to recapture our early form
"It's all a matter of finding the right balance with the car - when we do that, we will be back in the points."
As a result, Force India are now under pressure from the much-improved Sauber who are just 17 points off the pace with four races remaining.
"Sauber have been doing a very good job lately," conceded the Force India owner. "They are the in-form team at the moment and they have been taking all the opportunities that were presented to them.
"It's going to be a real fight in these last four races: we need to make a step forward to hold them off, because they can qualify well and they have strong race pace as well."