Ersson turned aside eight of the nine shots he faced after replacing Linus Ullmark (undisclosed) to begin the third period of Monday's 4-1 win over the Bruins.
Ullmark was shaken up late in the second period after a collision with JJ Peterka, but per Bruce Garrioch of Postmedia, Senators coach Travis Green indicated his removal for the final frame was just precautionary. The decision still resulted in Ersson seeing his first action for his new team in a relatively low-stress situation, as Ottawa held a 4-0 lead after two periods. Ersson likely would have been in line anyway to get his first start of the season Tuesday in Detroit, but the Sens may need to summon help from AHL Belleville to back him up if Ullmark needs additional recovery time.