Daniel Ricciardo has suggested that Red Bull have overtaken Williams in terms of pace, but still trail Mercedes and Ferrari.
The former constructors' champions have endured a difficult start to the season, with Ricciardo and teammate Daniil Kvyat collecting just 11 points from the first two races.
However, speaking after the second free practice session at the Chinese Grand Prix, Ricciardo has claimed that Red Bull might be making progress.
He told reporters: "Hopefully, the leaderboard is not lying too much. Today looked good but I don't want to jump to conclusions yet.
"I still think Mercedes for sure are quicker but Ferrari as well is at the moment a small step ahead.
"We seem to be a bit quicker than Williams at this stage. They always seem to come on a bit stronger on Saturday but for now we seem to be the third-best team and we're trying to at least hold that."
Ricciardo was the only non-Mercedes Grand Prix winner in 2014, taking three race victories last season.