Daniel Ricciardo has warned championship leaders Mercedes about Red Bull's pace after closing the gap to Brackley based outfit in second practice in China.
Mercedes has maintained an advantage of around one second over their nearest rivals during the first three races of the season, but Red Bull and Ferrari seem a lot closer this weekend in Shanghai.
"I would like to think we have caught up, but I think they have got a bit more in there," Ricciardo said post practivce.
"We are making small improvements. The gap is a big one so it is not going to come over one race, but I feel we have crept up a little bit more. It is still a big one but we are coming. Bit by bit we will get there, and hopefully before too long we will get close,'' he added.
Sebastian Vettel wasn't as optimistic as Ricciardo, suggesting that Mercedes are merely sandbagging.
"Maybe they didn't run full beans today, so it's difficult to say. They are still the favourites and they are still quite far away,'' the four time world champion said.
"I was behind the Mercedes on the long run and it looked like they could do what they want.
"I think for us it was a good day but not yet at their level,'' he added.