Ricciardo was third and fifth fastest in the two Friday sessions in Melbourne, ending practice two more than a second down on pacesetter Lewis Hamilton's best time.
But Ricciardo insisted that Mercedes is not as far ahead as it appears, and is confident he and team-mate Max Verstappen will be closer to its pace later in the weekend as Red Bull's set-up experiments did not pay off on Friday.
"We made some changes [that] probably didn't work out the way Max and myself wanted or expected," said Ricciardo.
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Red Bull's Australian driver Daniel Ricciardo speeds through a corner during the second practice session at the Formula One Australian Grand Prix in Melbourne on March 24, 2017.

Image credit: AFP

"I don't think they're [Mercedes] insanely quick; sure, they are quicker than us at the moment.
"[But] I feel we can still reel some of that advantage in that they've got."
Ricciardo is hopeful that if Red Bull can improve the set-up for Saturday, it could be in a battle for second-best behind Hamilton that might include new Mercedes driver Valtteri Bottas.
"It's fair to say they didn't work as much as we'd like so we'll probably go back a bit and then understand what we can do better for tomorrow.

Red Bull's Australian driver Daniel Ricciardo looks on after the second practice session of the Formula One Australian Grand Prix in Melbourne on March 24, 2017.

Image credit: AFP

"Mercedes sure is quick but it's more Lewis than Valtteri.
"Valtteri at the moment looks like he's in our group, or in a group with Ferrari, but I think we can be there.
"This weekend with the right set-up and the right lap in quali we can mix up with Ferrari.
"If Lewis does a perfect lap with his car, then that'll be a stretch to take pole - but we're not too far off. It's more encouraging than not."
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