Robinson entered his debut season with Montreal with 680 victories in 11-plus seasons as a manager. The Expos did not reach 20 victories last season until May 27, but Robinson has been able to turn around one of the National League's worst teams.
The game was tied 2-2 when Truby doubled off San Francisco starter Russ Ortiz (3-2) with one out in the seventh. Wilkerson followed with a single and Truby scored after right fielder Reggie Sanders misplayed the ball.
Orlando Cabrera added a sacrifice fly in the eighth inning as the Expos won for third time in four games following a six-game slide.
Armas (5-3) allowed two runs and five hits while striking out six. He won for the fourth time in five starts and defeated the Giants for the first time in four tries.
Rookie T.J. Tucker and Scott Stewart combined to pitch two perfect innings before Matt Herges struck out Tsuyoshi Shinjo to end the game and earn his sixth save.
Truby gave Montreal a 1-0 lead in the second with an RBI single, but Barry Bonds tied it in the fourth with a opposite-field homer off Armas. It was Bonds' 57th career home run against the Expos, tying Hall of Famer Mike Schmidt for most vs. the franchise. Bonds has 12 homers this season and 579 in his career, four behind Mark McGwire for fifth place all-time. Robinson is fourth with 586.
Vladimir Guerrero put the Expos ahead with his 11th homer, a solo shot off Ortiz in the sixth.
But Damon Minor, who started in place of J.T. Snow, opened the seventh inning with his first homer since Sept. 30, 2000 to forge a 2-2 tie.
Ortiz allowed three runs and seven hits in 6 1/3 innings. He struck out five but left after surrendering Wilkerson's go-ahead single.