During BSC Glasgow’s cup run, Thomas scored in the dramatic 4-3 upset win away to League One promotion challengers, East Fife, and grabbed the opening goal in the 3-1 win over fellow Lowland League club, East Kilbride, which set up Sunday’s tie.
Thomas said: “We’ve had a great cup run. It’s the biggest game of the season for us and we’re really looking forward to it.
“If we can get to the last eight, it’ll be a great achievement – we’d be the first non-league team to do it in a long time.”
The match is live on BBC One Scotland from 12 noon – watch it here.