Brazilians Senna (l) and Barrichello (r) offered contrasting qualities for Brawn
Rubens Barrichello has admitted an element of "luck" in being named Brawn GP's second driver and sympathises with Bruno Senna, his rival for the spot.
Senna was expected to get the nod from Honda for 2009 after impressing in testing but the team withdrew and was bought out by ex-team boss Ross Brawn.
And, with little preparation time remaining, he opted for Barrichello, Formula One's most experienced driver.
"I'm just lucky that at this time F1 has changed a little bit," he admitted.
"Because of the lack of testing, it is going to more experienced drivers again but I wish Senna all the very best," added the 36-year-old after the first day of a four-day test session at the Circuit de Catalunya on Monday.
Senna has done fantastically well and has a future in Formula One
"We're good friends, and although we haven't talked for the past couple of months when we've been fighting for a position, it has nothing to do with us.
"It was sheer coincidence that we ended up at the same place at the same time.
"For someone who has three or four years of experience, he has done fantastically well and he has a future in Formula One.
"I haven't seen anyone just yet with the capability of running for three years in cars, and all of a sudden getting to Formula One and doing so well like he did in testing."
Fellow Brazilian Senna, 25, has three years experience as a racing driver and came second in the GP2 Series in 2008.
Until Honda's announcement in December that it was pulling out of F1 because of the global financial crisis, the F1 team had been testing the youngster along with Britain's Jenson Button.
But F1 has banned testing during the season as part of cost-cutting measures, duly putting more of a premium on experienced drivers.
And Barrichello, who worked closely with Brawn when the Briton was technical director at Ferrari, has 270 starts under his belt.
Talking about the selection process, Brawn told BBC Sport why Barrichello got the drive for 2009.
"Jenson was an automatic choice to carry on for the team and he has done a great job in testing," he said. "Rubens was the preferred choice [as the second driver].
"He still has a huge amount left in him and he has shown incredible commitment and enthusiasm. I'm very excited to be working with both drivers.
"We made no commitments with Bruno. We kept in touch but circumstances have worked against him."
Going into the 2009 season - which starts with the Australian Grand Prix on 29 March - Toro Rosso's Sebastien Buemi, from Switzerland, will be the only rookie on the starting grid.