Webber and Berger celebrate birthdays on Thursday
Australian Mark Webber, who recorded his first victory last month at the Nurburgring, is 33, while 10-time winner and former team boss Gerhard Berger turns 50.
Austrian Berger disappeared from the paddocks after last year's championship, when he sold back his 50 per cent share in Toro Rosso to Red Bull's Dietrich Mateschitz.
"I am a private citizen, unlike Didi who has a company in the background," he said, as he explained to Germany's Auto Motor und Sport his reasons for leaving F1.
Berger however refuses to rule out coming back to the sport he loves at some point. "If the right task comes along, I would participate again," he promised.
Webber, meanwhile, is in contention for the 2009 world championship, but his chances took a hit at Valencia last weekend when after struggling for pace he lost his second place in the drivers' title to Rubens Barrichello.
But Red Bull is expected to be right back on the pace at Spa this weekend, and Webber is not giving up the championship fight.
"At the moment it looks like Jenson (Button) is in the right position … I'm a bit closer, Sebastian (Vettel) a little bit further away, but it's still a long, long way to go," he is quoted as saying by the Australian news agency AAP.