Sebastian Vettel is not expected to be in the RB9 until the third day of Jerez testing.
Jan.23 (GMM) Mark Webber will give Red Bull's 2013 car, the RB9, its track debut at Jerez early next month.
Brazil's Totalrace added that German Vettel will drive on day three.
Webber, 36, also debuted Red Bull's championship winning 2012 car.
"I think - especially in the race - Vettel will still have his nose in front this year, but maybe in qualifying Webber can be there," former F1 driver Nick Heidfeld told Speed Week.
"The team probably put more into Vettel, as they know now very well that he can deliver the title, and also it's likely that Sebastian is going to stay longer than Webber," he added.