Ezekiel Elliott scored on a 1-yard run to ignite a comeback from a seven-point deficit and Brett Maher kicked three field goals as Cowboys (2-1) beat the Giants (2-1) for the 10th time in 11 games.
Cooper Rush threw for 210 yards, including the 1-yarder touchdown to Lamb, in winning his second straight game filling in for the injured Dak Prescott (thumb).
Saquon Barkley scored on a weaving 36-yard touchdown run that gave the Giants a brief 13-6 lead. Graham Gano added three field goal, including a 51-yarder with 3:37 to play to make it a one-score game.