Downs underwent an MRI on Friday that revealed no significant damage, and manager Mike Scioscia said had the club needed Downs on Sunday, he would have used the veteran left-hander.
In 3 1/3 innings this season, Downs hasn't allowed a run and has surrendered three hits, including a double to Josh Reddick in Monday's 6-0 victory.
Scioscia also said righty reliever Bobby Cassevah is close to returning after he began the season on the disabled list with shoulder inflammation.
Cassevah hasn't allowed a run in each of his four one-inning outings with Class A Inland Empire. Scioscia said his velocity has improved since he began throwing there.