Daniel Ricciardo says Red Bull appear to be the best of the rest behind Merc and Ferrari, but warns Williams could still hit back on Saturday in Shanghai.
Red Bull slipped to fifth fastest in Malaysia as they not only fell behind Williams, but also sister squad Toro Rosso with Daniil Kvyat and Ricciardo finishing ninth and 10th respectively.
However, the team did have various technical issues at Sepang, but they are confident those problems have been fixed ahead of the Chinese Grand Prix.
Ricciardo was third fastest in FP2 on Friday, 1.092s behind pacesetter Lewis Hamilton of Mercedes, while his team-mate Daniil Kvyat was down in sixth.
"It was definitely a positive day for us. We did more laps and more understanding with those laps. I think on both tyres, also short and long runs we’re pretty happy," the Australian said.
"We had new parts on the car; they all seem to work, so that’s good for now. I definitely feel more confident. Even my satisfaction when driving the car this afternoon: I felt the grip; I really feel the improvements that the car’s made, so that’s always nice.
"I’m positive it can be a good weekend."
Although Mercedes and Ferrari and Ferrari are still out of their reach, Ricciardo is happy with the steps Red Bull have taken forward.
He added: "Today looked good but I don’t want to jump to conclusions yet. We look closer. I’d still think that Mercedes for sure are quicker and Ferrari as well at the moment are a small step ahead. But I think we’ve closed that step a bit.
"We seem to be a bit quicker than Williams at this stage. But they always seem to come on a bit stronger on Saturday.
"For now we seem to be the third best team and we’re trying at least to hold that."