ATLANTA -- Braves reliever Luke Jackson has ligament damage in his right elbow, and there is no timetable for his return.

A key part of the bullpen last year during Atlanta's run to the World Series championship, Jackson is having a "comprehensive evaluation," the team said Saturday.

The Braves said tests revealed damage to the ulnar collateral ligament in Jackson's elbow. The 30-year-old had the test after he was shut down for a week and then had renewed discomfort when he resumed throwing.

Problems with the ulnar collateral ligament can lead to Tommy John surgery, which would end Jackson's season.

Jackson posted 18 saves in 2019 and has since served as one of the team's top setup men. He was 2-2 with a career-best 1.98 ERA in 71 games in 2021, helping Atlanta win its first championship since 1995.

He had a 0.00 ERA in three World Series games against the Houston Astros, allowing one hit in 3⅔ innings.

The bullpen is one of the Braves' deepest areas following the offseason additions of closer Kenley Jansen and Collin McHugh. If Jackson is unavailable, McHugh's role becomes especially important as another right-hander in the bullpen.