The 39-year-old Thomas got into Dallas' game on Saturday night against Minnesota after Kari Lehtonen sustained a head injury. Thomas got the starting nod Monday night at home against Columbus, and Lehtonen sat out.
Thomas stopped all six shots he faced on Saturday to earn the win in his Stars debut.
Cristopher Nilstorp, recalled Sunday from Texas of the American Hockey League, served as the backup to Thomas — a two-time Vezina Trophy winner. Nilstorp has played in five career NHL games.
Lehtonen is listed as day to day.