By Peter Abraham, Globe Staff

ST. LOUIS — Shane Victorino is available to come off the bench for the Red Sox tonight and manager John Farrell is optimistic his right fielder will be able to start Game 6.

Victorino's season-long issues with his lower back flared up again on Sunday and he did not play in Game 4.

Victorino was willing to start, but the Sox didn't want to take a chance.

"He's available off the bench. But didn't want to get into a situation, not knowing how long he can go, that we'd end up losing a player. So we can use him a little bit more at our discretion in this role," Farrell said.

"Pressed into it, probably [could] start him. But with some uncertainly there on the duration, don't want to end up losing out on him and using somebody else who might have to pick him up."

Victorino has responded well to treatment and could return to the lineup on Wednesday.

"Very good," Farrell said when asked how he felt about Victorino starting Game 6.