The Brumbies have made just one change to the starting side which beat the Reds last week, with Joe Tomane being given the nod to start at 14.
Tomane starts ahead of Fijian flyer Speight, who will sit out this weekend's match with the Rebels after suffering bruising to his ribs during the week one clash with the Reds. The Australian Conference's top try-scorer in 2012 was cleared of serious damage to his ribs earlier in the week.
With Tomane moving to the starting side, young gun Tevita Kuridrani makes his first appearance of 2013 on the Brumbies bench.
Ruaidhri Murphy drops from the 22 for Saturday's game in Melbourne with Scott Sio claiming the 17 jersey. Like Kuridrani, it's Sio's first appearance for the season having played four times for the Brumbies during his debut year in 2012.
White said playing away from home in an Australian derby was always a huge challenge and that Saturday's clash with the Rebels would be no different.
"It's an Australian derby so you know it's going to be a tough, passionate game with plenty of feeling," he explained.
"That Rebels starting side has six internationals and another handful of guys, like Mitch Inman, who have been involved with the national camps recently. Those are the sorts of players our guys want to play against to the test themselves with the best.
"There's no doubt the Melbourne crowd will be behind the Rebels, they are very passionate about their sport in that part of the world. But I'm confident we'd done the hard work and should be good enough to leave Melbourne with a win."
Brumbies: 15 Jesse Mogg, 14 Joe Tomane, 13 Andrew Smith, 12 Christian Lealiifano, 11 Clyde Rathbone, 10 Matt Toomua, 9 Nic White, 8 Ben Mowen (c), 7 David Pocock, 6 Peter Kimlin, 5 Sam Carter, 4 Scott Fardy, 3 Dan Palmer, 2 Stephen Moore, 1 Ben Alexander.
Replacements: 16 Siliva Siliva, 17 Scott Sio, 18 Fotu Auelua, 19 Colby Faingaa, 20 Ian Prior, 21 Robbie Coleman, 22 Tevita Kuridrani.
Date: Saturday, 23 February
Venue: Suncorp Stadium, Brisbane
Kick-off: 19:40 (08:40 GMT)
Referee: Chris Pollock (New Zealand)
Assistant referees: Andrew Lees (Australia), Rohan Hoffmann (Australia)
Television match official: Steve Leszczynski (Australia)