Although Leclerc won the last two races in Belgium and Italy, Ferrari have been tipped to struggle by comparison around Marina Bay, a much slower and twistier circuit than Spa-Francorchamps and Monza, where the SF90's straight-line power was on display.
Speaking after Ferrari's first home win in nine years, Binotto said the search for additional downforce had already begun and the team will arrive ready for the street race with some new parts.
Binotto said: "Coming from back to back victories is a good feeling for the team and for our tifosi, but in reality these victories are already behind us and we are well aware that Singapore will present new challenges and a layout in which our car is not as strong as at other circuits.
"We are bringing a few new parts there as part of our effort to close the gap to the competition, at a track that features predominantly slow speed corners.
"All of this, together with the traditionally eventful close racing in between the barriers, on the city streets – conditions that both Sebastian and Charles love very much – will certainly make for a tough but exciting race weekend."
Vettel finished a distant third in Singapore last year, having seen his race ended at the first corner in 2017 amid a spectacular crash with then-teammate Kimi Raikkonen and Max Verstappen.
Having come out on the worst side of Singapore's often unpredictable nature in the past, Vettel does not rule out benefitting in 2019.
He said: "We have seen before that anything can happen in this race, so the final result is hard to predict."
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