The game will be televised (tape delay) on Fox Sports at 1 p.m. ET.
A loss would eliminate the Claymores from World Bowl contention, as the league's top two teams earn a berth in the title game.
The Claymores take back-to-back wins into the contest. Not only do they need to make it three in a row, they also neet to win by more than seven points to take the head-to-head tiebreaker with the Dragons.
Nall will lead Scotland's top-ranked offense takes on Barcelona's fifth-ranked defense.
In other games, Berlin visits Amsterdam on Saturday, while the first qualifier for World Bowl XI could be decided Sunday as Rhein visits Frankfurt.