Day will be added to the active roster and suit up against Montreal on Tuesday, Joe Smith of The Athletic reports.
Day will be making his NHL debut after spending the previous four seasons developing in the minors. Selected by the organization in the third round of the 2016 NHL Draft, the Belgian blueliner has garnered two goals and 11 assists in 19 games for the Wolf Pack this year. Once the Lightning get fully fit defensively, Day figures to return to the taxi squad or minors.