Merilainen was sent down to AHL Belleville on Friday.
Merilainen was recalled from AHL Belleville on Tuesday to serve as the backup against Utah, TSN 1200 Ottawa reports.
Merilainen (groin) will be in the lineup for Sunday's preseason contest against Pittsburgh.
Merilainen has not participated in training camp yet due to a groin injury that occurred during rookie camp, per TSN 1200 Ottawa.
Merilainen is dealing with a groin injury that isn't expected to be serious, Bruce Garrioch of Postmedia reports.
Merilainen was recalled from AHL Belleville on Saturday.
Merilainen was sent to AHL Belleville on Friday.
Merilainen stopped nine of 12 shots before being replaced by Mads Sogaard early in the second period of Thursday's 7-2 loss to the Panthers.
Merilainen will be between the visiting pipes in Florida on Thursday, Wayne Scanlan of the Ottawa Citizen reports.
Merilainen stopped 34 of 37 shots in the Senators' 3-2 overtime loss to the Hurricanes on Tuesday.