IRVINE, Calif. -- New Orleans Saints rookie quarterback Spencer Rattler missed practice Sunday with a thigh contusion, a day after he led the Saints to a late field goal to beat the Arizona Cardinals in their preseason opener.

Saints coach Dennis Allen said he doesn't expect the injury from Saturday's game to be anything serious.

"He was fighting to get out here to practice," Allen said. "It was more of precautinaty measure on our training staff's part."

In his first preseason game in the NFL, Rattler played the entire second half. He finished 9 of 17 for 70 yards. He ran for a 4-yard touchdown and also engineered the winning score, driving the Saints 56 yards in 12 plays and 1:50 to set up Charlie Smyth's game-winning 37-yard field goal with 5 seconds left.

Rattler, a fifth-round draft pick this spring, has been impressive in his first training camp and is in a battle with second-year quarterback Jake Haener to be Derek Carr's primary backup.

Allen said last week he wanted to use the preseason to see whether Haener or Rattler could handle the backup job. Neither has ever played in a regular-season game.