Campbell was called up from the Texas Stars of the AHL on Thursday along with defenseman Patrik Nemeth. Lehtonen replaced Niemi in the second period of Tuesday's loss to Ottawa but left after just 8 minutes with an upper-body injury.
The 23-year-old Campbell is 3-3 with a 3.8 goals-against average and .873 save percentage. The Stars' 2010 first-round pick started the season on the non-roster list in Texas after getting hurt during the preseason.
Nemeth finished a 14-day conditioning assignment with Texas, getting one assist in eight games. He has appeared in two games for Dallas this season.