CHICAGO -- Cubs third baseman Aramis Ramirez told ESPNChicago.com that he aggravated a left thumb injury on a swing during Friday's game against the Cincinnati Reds.
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Ramirez, who did not start Saturday's 3-1 victory and sat again Sunday, said he was unsure when he will be able to return as he works with team trainers to rehabilitate the thumb.
The struggling third baseman, batting .177 with six home runs and 23 RBIs, missed 15 games last month with the injury.
Ramirez was batting .273 in 22 at-bats since coming off the disabled list June 25.
Bruce Levine covers baseball for ESPNChicago.com.