From Baseball Reference:

1984 — The Detroit Tigers suffer their first loss of the season after nine consecutive wins. The Tigers fall to the Kansas City Royals and rookie Bret Saberhagen, who earns his first major league victory.

Final score: Royals 5 – Tigers 2. Interesting that Dan Petry gave up five runs and Sparky still let him pitch eight innings.

Gibby hit a solo shot off Dan Quisenberry in the ninth, but it wasn’t enough. With the win, the Royals pushed their record to 6-6. Quisenberry earned saves in five of the wins.

Check out the boxscore.