The following year, Mendoza struggled to a 9–9 record with an ERA of 4.29 in innings pitched. That year, he started only six games and was quickly moved to the bullpen. He gave up 68 runs that year, a career worst, and was left off of the roster for the 1999 American League Division Series. He rejoined the team for the Championship Series, where he pitched innings and pickup up a save. In the World Series, he pitched innings of relief and surrendered 3 hits and 2 runs, all earned, however, he still earned the win as the Yankees went on to sweep the Braves, 4–0.