Callahan, 22, made his NHL debut on March 25 against the Columbus Blue Jackets. He was second on the Grand Rapid Griffins of the American Hockey League with 26 goals and fourth with 44 points in 70 regular-season games.
Callahan was a sixth-round pick (No. 180) in the 2009 NHL Draft.
Nestrasil, 23, had 16 goals and 36 points in 70 games for the Griffins. He was a third-round pick (No. 75) in 2009.
We have no doubt how he can play. You don't, with four teams that are left, you're not getting here without good goaltending. All great goalies left, and [Bishop] is a top-tier goaltender in this league and he's shown it.
— Lightning coach Jon Cooper on goalie Ben Bishop, who shut out the Rangers in Game 5