To be fair, this rumours came mostly from outsiders, who had no idea of the rivalry between FCS, where most Saarish footballers played, and Lautern, the team that many DFB players played for. Many Saarish had loved their team to defeat Germany, regardless of their self-definition as Germans, only for this fact. The atmosphere at Ludwigspark was very friendly, though.
By the way: Mostly identified as Germans is an understatement. Even those, who voted in favour of the autnomy act identified as Germans and Germans only. That talk about a never existing French minority was a French invention to justify their exploitation of Saarish mines and steeling industry.