Gary Carter, the most valuable player in Sunday's All-Star Game, doubled home the tie-breaking run and Tim Wallach had a run-scoring single in the eighth inning to lead Montreal over Pittsburgh before 37,275 at Olympic Stadium.
Andre Dawson led off the eighth with a double against reliever Pascual Perez (2-3) before Carter doubled to left. After Warren Cromartie was intentionally walked, Wallach followed with a single to center. c
Bill Lee (2-2) yielded only one hit over the final four innings to record the victory.
The Expos took a 1-0 lead in the first inning on Dawson's solo homer off Jim Bibby. It was his 14th home run of the season and 100th of his career.
Pittsburgh was retired in order by Scott Sanderson in the first two innings but got the run back in the third. Tony Pena started with a one-out single, moved to second on Bibby's sacrifice and scored when Omar Moreno singled to center.
Sanderson threw 56 pitches before leaving after five innings. He held the Pirates to only two hits. Bibby game way to reliever Victor Cruz after giving up four hits in 4 2/3 innings.