Sebastien Buemi believes Toro Rosso's chances of beating Sauber to eighth place in the constructors' championship depend on how quickly it can get its F-duct working effectively.
STR became the last of the established squads to introduce an F-duct when it ran the device briefly in Friday practice at Monza last week, but the system's debut proved disappointing and it was removed for the rest of the weekend.
Buemi remains confident that the F-duct can deliver a major boost to Toro Rosso, and hopes it will be more effective in Singapore. The team is currently 17 points behind eighth-placed Sauber in the standings.
"It is always difficult to quantify what you can gain with the F-duct," said Buemi in an interview for the team's official podcast. "But one thing that is for sure is that if you can get it to work properly, it's [worth] between two and six/seven tenths - it depends on the circuit.
"So we've got to make it work, because this is the way we will be able to fight against Sauber and finish ahead of them in the championship. So we are putting all our effort together to make it work for Singapore. But it's going to be difficult.
"We are now working hard in the windtunnel to find out why it did not really work and then we will see if we can have it for Singapore."
Team boss Franz Tost said the aim was to keep the F-duct on throughout the weekend in Singapore.
"It's the hope that we can race it there," he said in the podcast. "We just have to analyse why it didn't work so well [at Monza] on Friday. But I'm convinced that our engineering department will find the solution."
Tost felt that Toro Rosso's Monza form was very encouraging, as Buemi finished just outside the points in 11th, but right on 10th-placed Rubens Barrichello's tail after a race-long battle with the Williams.
"We were only one second behind the fastest lap time," Tost noted. "I think that from the technical side the team made a step forward with bringing the lower exhaust system, which brought us more downforce.
"Apart from the F-duct, I think that in setting up the car we made a step forward. We must not forget that we have two very inexperienced drivers, but they are learning very fast, and in the meantime I'm quite confident and convinced that they know how to set up the car, and they made a step forward in how they do this procedure. So I'm quite optimistic."