The vagabond Expos, who won’t play in Montreal until April 22, have outscored the Braves 13-2 in the first two games at Turner Field. Atlanta is 0-2 for the first time in six years.
Vidro hit a two-run shot in the first inning, sending rookie Braves starter Horacio Ramirez to a hard-luck loss in his major league debut.
Day, making just his third big league start, dominated a Braves team that looked downright feeble offensively.
Atlanta got only one runner past second base.
The 24-year-old right-hander allowed just three hits in seven innings, and only one of those was hit hard. He walked two and struck out three.
Day (1-0) earned a job in the starting rotation during spring training after working mostly out of the bullpen last season.
He won four games — all in relief.
Rocky Biddle struck out two in the ninth for his second career save.
The Braves had not lost their first two games since 1997, when they dropped a pair of one-run decisions at Houston. They quickly rebounded, going on to win 101 games and the sixth of their 11 straight division titles.
The Expos, following the pattern of their 10-2 victory on opening day, jumped ahead of the Braves just six pitches into the game.
Montreal scored four runs in the first against Greg Maddux on Monday.
This time, Endy Chavez led off with a single to left and Vidro hit a 1-2 pitch into the left-field stands. Ramirez hung a breaking ball after throwing over three times to first, trying to keep Chavez close to the bag.
Ramirez settled down after his shaky start, pitching seven innings. The 23-year-old left-hander allowed only four more hits, walked one and struck out five. Of his 91 pitches, 63 were strikes.
The Expos added an insurance run in the ninth on Chavez’s two-out single off Darren Holmes