Smith hasn't made an appearance for the Guardians since their June 22 win over the Athletics due to back spasms, MLB.com reports.
Smith threw prior to Wednesday's 5-4 loss to the Cubs and is considered day-to-day. The right-handed reliever has collected two wins, three saves and 15 holds over his 36 appearances this season while logging a 2.36 ERA, 1.17 WHIP and 53:13 K:BB over 34.1 innings.