Ricciardo said that the team made changes to the car between the third practice session and qualifying.
"I think [I'm] surprised at sixth but obviously a few guys opted for the prime, so whether we'd have stayed there, who knows?" Sky Sports News quotes Ricciardo as saying.
"I knew Q3 wasn't impossible. I knew it was probably going to be a little bit harder than it was last week; that was realistic. But I knew that if we got our stuff together, we'd have a good crack.
"It worked well. After P3 we made some needed changes; they helped us out a bit and pushed us forward. Then I put a lap together in Q2 that did us a favour."