Complex sentence: Then-mayor of Quebec City, Lucien Borne, was in attendance, which saw more than 5,000 people attend that game with the Athletics winning their first game at the stadium 6-5 against Trois-Rivières.
Split into simpler sentences: Then-mayor of Quebec City, Lucien Borne, was in the attendance. The Athletics won their first game at the stadium 6-5 against Trois-Rivières.