Grab tickets and join the crowds at a game at Stade de Geneve. If there's nothing on while you're there, you might like to check if the stadium offers a tour of the grounds.
This sporting facility is on the to-do lists of many visitors to Lancy. But Stade de Geneve isn't the only drawcard in the area. United Nations European Headquarters, Palexpo, and Jet d'Eau Fountain are some other worthwhile sights close by.