Wales face a strong Belgium side as they look to start their qualification campaign for the next World Cup with a win, and Southall has insisted that he would be "disgusted" if there was not a capacity crowd in place this evening.
Southall said: "I'd be disgusted if the stadium wasn't full. I'd be disgusted with the Welsh FA and disgusted with the people that are not coming.
"You don't realise the effect that people can have on the team and the lack of people can have on the team.
"I've played at Cardiff Arms Park against San Marino and we could hear them ordering their cups of tea and hamburgers at half-time. There's nothing more depressing than that."
Southall won 92 caps for Wales in an international career spanning 15 years.