O'Malley went 2-for-5 with an RBI single in Friday's 12-1 loss to the Cubs.
The Mariners' leadoff man allowed his team to avoid the indignity of a shutout with a ninth-inning single that plated Leonys Martin. The 28-year-old has a pair of multi-hit outings in the last five contests, but has only tallied two extra-base hits, both doubles, in his 11 hits during July.