Bottas set the day's overall fastest lap in the opening session with a time of 1:18.148 seconds on the soft tyres, a remarkable 0.849 faster than Hamilton who won from pole in Spain previous year.
Red Bull's Ricciardo had a testing first practice session and lost control of his vehicle after some oversteer to crash out.
That essentially neutralised the session whilst the VF18 was loaded onto the recovery truck; the green lights returned with one hour and 16 minutes on the clock.
The reigning constructors' champions still have plenty to be wary of, though, after seeing Ferrari and Red Bull closing the gap.
Hamilton said: "It is going to be relatively close between the top three teams but I can't really say who is quickest at the moment".
On Thursday, Miami officials voted in favor of a Formula One proposal that would have the city host a Grand Prix on its downtown streets some time next year.
Lap times were considerably faster than 12 months ago around the Circuit de Barcelona-Catalunya partly due to softer tyres being used this year but mostly because of a new track surface which has significantly increased the grip level.
Bottas was a tenth of a second faster in the morning session than Hamilton's afternoon time at the 4.6-kilometer (2.8-mile) track outside Barcelona.
The virtual safety auto was deployed in the morning when Ricciardo's vehicle ran across the gravel and into the barriers.
Kimi Raikkonen would be sixth after seeing his day ended early by an engine problem, with a tell-tail puff of smoke from the back suggesting he will likely require a new unit for final practice on Saturday.
Robert Kubica completed his first practice session of the year with Williams and drove Sergey Sirotkin's auto to the 19th fastest time.
Kubica, who had a spin toward the end of the session, finished with the second-to-last time - in front of teammate Lance Stroll. "But I'm satisfied with the session and with how I reacted to hard conditions".
Stroll almost hit the tyre barriers after going off the track with about a half-hour left in the first session.
"It was so windy out there and every driver was struggling with the changing direction of the wind".