The Astros selected Lambert's contract from Triple-A Sugar Land on Friday, Julia Morales of Space City Home Network reports.
Lambert made a bid for the Opening Day roster with an encouraging spring training and remained effective at Triple-A to begin the season, as he logged a 1.84 ERA, 0.96 WHIP and 12:3 K:BB across 14.2 innings with Sugar Land. He'll now be the 10th pitcher to start a game for the Astros this season, as he's set to take the mound Friday against the Cardinals.