Nicky Hayden rode alongside eight different team-mates during his 13 seasons in MotoGP, which came to an end at last month's Valencia season finale.
So which of them impressed the 2006 world champion the most?
“I could write a book on my team-mates because there have been a lot of different personalities over the years and I've learned a lot from each one,” Hayden said.
“For sure, Casey for outright speed was incredible. His ability to find the limit on a wet or dirty track is something I'd never seen before. And you know Dani, the way that he gets the bike off the corners is incredible.
“But I think the person who impressed me the most has to be Valentino. Because I was his team-mate twice and the Ducati days when it was really low - for him to come back from that is extremely impressive.
“And at 36, to have as much success and money - he has everything. But to still have that same passion and fire is something that I found motivating. I think that's been more impressive than anything on track.”
Hayden is moving to WSBK in 2016, riding for the Ten Kate Honda team.
Nicky Hayden's MotoGP team-mates:
2015 - Eugene Laverty (Aspar Honda)
2014 - Hiroshi Aoyama (Aspar Honda)
2013 - Andrea Dovizioso (Ducati Team)
2012 - Valentino Rossi (Ducati Team)
2011 - Valentino Rossi (Ducati Team)
2010 - Casey Stoner (Ducati Team)
2009 - Casey Stoner (Ducati Team)
2008 - Dani Pedrosa (Repsol Honda)
2007 - Dani Pedrosa (Repsol Honda)
2006 - Dani Pedrosa (Repsol Honda)
2005 - Max Biaggi (Repsol Honda)
2004 - Alex Barros (Repsol Honda)
2003 - Valentino Rossi (Repsol Honda)