The Chicago Bears had ceased playing NFL football in Wrigley Field after the 1970 season.
A different kind of football -- the one we Americans call "soccer" -- debuted in Wrigley Field in 1978 as the North American Soccer League's Chicago Sting began playing part of its schedule at Wrigley, after having played their first three seasons at Soldier Field.
The Sting wasn't a very good team to start their 1978 season. They had lost their first five games before coming "home" to Wrigley for the first soccer game there on a Saturday afternoon in April while the Cubs were in Atlanta getting shut out by the Braves 5-0 Mike Conklin of the Tribune summed up the soccer action from Wrigley:
This time the Chicago Sting outdid themselves. Not only did they find a new place to lose, they did it in unique fashion before 4,521 fans. Despite playing with an extra man for almost two-thirds of the match following the ejection of a Minnesota player, the Sting still managed to lose 1-0. It was the sixth defeat without a win for Chicago this season and spoiled the club's debut in Wrigley Field, where they've scheduled 8 of their 15 home games this year. The 0-6 start equals last season's club record for inefficiency, and Wrigley Field now joins the impressive growing list of locations where the Sting has picked up defeats in 1978 -- RFK Stadium, the Meadowlands, the Kingdome, Soldier Field, and the Oakland-Alameda County Coliseum among the others.
The Sting actually wound up starting 0-10 that year before a hot finish got them into the NASL playoffs. Three years later, splitting their home-game time between Wrigley Field and Comiskey Park, attendance soared. One Wrigley game drew 30,501. The Sting won the 1981 league championship, the "Soccer Bowl," which was played at Exhibition Stadium in Toronto, and given the lack of interest in soccer in the USA then, that game wasn't even televised live.
The club also played indoor soccer in the Major Indoor Soccer League (MISL), and eventually, with flagging interest in the outdoor team, they folded after 1984. Outdoor soccer has done much better in the USA with the creation of Major League Soccer (MLS) and the construction of venues, like Toyota Park in Bridgeview for the Chicago Fire, that are much more suitable for soccer than NFL or MLB parks. I attended one Sting game at Wrigley. The field was laid out identically to the one you see in the 2012 photo above, going from the third-base dugout to the right-field wall. It was an interesting diversion from baseball, for a day, anyway.
The Sting played 39 games at Wrigley Field between 1978 and 1984, going 28-11. If only the Cubs could play that well at home.