Jamie Alguersuari has confirmed that Toro Rosso will not run its F-duct at this weekend's Korean Grand Prix.
After conducting rigorous testing on the device during the final aero test session of the season, the team was left disappointed when it failed to meet expectations.
In his diary on the team's official site, Alguersuari admitted that the F-duct could have been beneficial on the Korean International Circuit's iconic 1.2-kilometre straight.
"Just before heading for Korea," he wrote, "I drove the STR5 in our last aero test of the season, when we took the decision not to run the F-duct in Korea. It was not producing the results we expected, which is a shame as it would have been an advantage for us given the layout of this circuit."
Although Toro Rosso first ran with the F-duct during free practice at the Italian Grand Prix, the unit has yet to make its race debut. The decision is a blow to the team, which now lies 26 points behind eighth-placed Sauber in the constructors' championship.
Despite this, however, Alguersuari believes Toro Rosso could still enjoy a successful weekend in Korea.
"I am still optimistic about the weekend," the Spaniard continued. "This track is new for everyone and the simulation tools the teams have will not be based on any previous data, which could put the big and small teams on a more equal footing.
"If we hit on something good in terms of running the car and work intelligently, maybe we can get a good result. Anyway, I'm looking forward to it as discovering a new track, a new country and a new culture is always exciting."