Victorino (back) day to day

BOSTON -- Outfielder Shane Victorino, who came out of Wednesday’s 6-5 win over Oakland in the sixth inning after jogging down to first base on a groundout, remains day-to-day with what manager John Farrell described as lower-back stiffness.

This was the second time in five games that Victorino was forced out midgame by back issues, having departed early Saturday, and he subsequently sat out Sunday’s double-header against the Royals.

Victorino has experienced back tightness in the past, but never missed more than a game on three previous occasions.

The Sox are noticeably weaker in the outfield without Victorino, who has made several outstanding plays in right field, most recently on Monday night, when he ran down Eric Sogard’s bid for extra bases with two on in the eighth inning and made a nice over-the-head catch.

The Sox didn’t have the option of recalling Jackie Bradley Jr., since he was just optioned back to Pawtucket and can’t be recalled for 10 days (unless the Sox plan to place Victorino on the DL, which is not in the works). They opted instead for catcher Ryan Lavarnway, who Farrell said would be used as a right-handed hitter off the bench.

Thursday night, Daniel Nava was in the lineup in right field, with Mike Carp in left. Remaining on the bench is outfielder Jonny Gomes, who has yet to knock in a run in 15 games this season and is batting .188 overall. The Astros are starting Philip Humber, a right-hander, but Gomes has actually fared better against righties this season (4 for 18, .222) than lefties (2 for 14), .143.

With runners in scoring position, Gomes is 0 for 3, though he also has drawn five walks (one intentional).

Lavarnway’s stay is expected to be a short one, Farrell saying that the catcher’s roster spot will be used when John Lackey comes off the disabled list. Farrell said all signs point to Lackey starting against the Astros on Sunday after a robust bullpen session here Thursday.