The RB driver banked the fastest time of the session after bolting on a set of red-walled rubber midway through the opening hour of running.
That catapulted the Australian to the top of the timesheets, ahead of McLaren’s Lando Norris and Oscar Piastri, who’d also performed a soft tyre run.
However, it proved a misnomer as the RB driver slipped down the order in the day’s latter session.
“Obviously, the morning we had a little five minutes of fame,” Ricciardo said.
“We knew obviously some, not many teams actually, put a soft on. So as much as it’s nice to see your name at the top, and obviously, the media get excited.
“We knew this evening would kind of settle a bit more and we’d get a bit more of a true picture of where we are.”
Ricciardo had played down RB’s chances following a promising performance in pre-season last week.
The performance in opening practice, with Yuki Tsunoda in fourth, suggested the initial impression from testing was fair.
However, once the field fitted a set of softs, the Faenza duo slipped down the order.
“I think we ended 12th but I do think we’ve got a little bit more than that,” Ricciardo said.
“I feel like we made some adjustments for the evening session but there’s a little bit more we can do.
“A good day, good testing for us, and see if we can crack into the top 10 for quali tomorrow.
“If we put it all together tomorrow, Q3 tomorrow and then points on Saturday – not Sunday,” he added.
“I’m fairly upbeat about the day.
“I know we’ve got some time to find but I feel like we do know some areas to find it, so I’m excited to get stuck into the data and speak to the guys this evening.”
Practice continues in Bahrain tomorrow (Friday) with a final 60 minutes of running at 15:30 (23:30 AEDT) ahead of qualifying at 19:00 (03:00 AEST Saturday).