The home side leads Pool 1 of the British and Irish Cup
Darren Cave will captain Ulster A in their match against London Scottish at the Kingspan Stadium.
Craig Gilroy will start on the left wing, with Robbie Diack in the second row.
The home side are top of their pool in the British and Irish Cup, with their opponents just three points behind.
Speaking to Q Radio sport, winger David Busby says there's no room for complacency.
Kick-off tomorrow evening is at seven o'clock.
Ulster A team to play London Scottish
(15-9) Rob Lyttle, David Busby, Darren Cave (C), Mark Best, Craig Gilroy, Johnny McPhillips, Jonny Stewart
(1-8) Tommy O'Hagan, Jonny Murphy, Ricky Lutton, Robbie Diack, John Donnan, Stephen Mulholland, Conor Joyce, Lorcan Dow
Replacements (16-22) Zack McCall, Craig Trenier, Alex Thompson, Connor Smyth, Johnny Creighton, Rory Butler, Jack Owens