World Superbike star Jonathan Rea made his Repsol Honda MotoGP debut aboard Casey Stoner's RC213V during testing at Brno on Monday.
The 25-year-old has been called up to replace the injured Stoner at the next two races, barring an early return for the Australian.
Rea, whose only previous MotoGP experience was a private test on an 800cc Honda in 2010, completed 61 laps of the Czech Republic circuit.
The Ulsterman's best time, set on his penultimate lap, was 3.145s behind fastest man Cal Crutchlow (Tech 3 Yamaha) and 2.892s from Repsol Honda's title contender Dani Pedrosa.
“It's an opportunity of a lifetime for me and I'm thankful to Honda for asking me to be here, although I'm gutted for the guys in the team and obviously for Casey as he is the guy that should be here and I wish him a fast recovery,” said Rea.
“My first impressions are that the bike isn't that difficult, it's the tyres and the way they work that I'm finding hard. I'm struggling to finish off the corner which is definitely a confidence issue as I just need to load the front and find that confidence but it's my first day and I don't want to find that limit, or risk overstepping it just yet.
“It's great to be able to see Dani [Pedrosa's] data and learn where to go fast, that's a big help. I don't underestimate how tough a job it is, I just need some time and I don' t feel pressure to perform, it's a learning process with the team and people around me.
“It's been a great day, one of the best days of my life. I've been a Honda rider all my career and now to ride the best Honda machine in the World has been a dream come true.”
Rea, a ten-time WSBK race winner, will take part in the Aragon test on September 4-5, prior to his scheduled MotoGP debut at Misano on September 14-16.
Stoner's recovery time is still unclear, but most expect the soon-to-retire double world champion to be absent until October.