Williams have "fairly healthy upgrades coming in Singapore" and head of performance engineering Rob Smedley hopes will help them to challenge Ferrari again.
Ferrari have been the second-best team behind Mercedes for most of this season, but Williams have shown glimpses of their 2014 form as they have three podiums to their name, the last of which came at Monza last time out.
However, the Grove-based squad will be the first to admit that Felipe Massa's P3 at the Italian GP was somewhat fortunate as Nico Rosberg retired late in the race while Kimi Raikkonen had to fight from the back of the field after a poor start.
Smedley, though, believes Williams will up their game again at the Marina Bay Street Circuit this weekend after they made some big upgrades to the FW37.
"I think Ferrari showed great pace," he is quoted as saying by Autosport. "They've done a really, really good job.
"They brought a new power unit which delivered in qualifying and the race.
"What we need to do now is to react to that. We've got some fairly healthy upgrades coming in Singapore.
"We just have to react, we have to keep bringing what we can bring in all the areas and we can't stand still.
"I'm hoping that with the changes we're going to make, we're going to be back on par with them in Singapore."