Archer (1-1) made his second start of the season and only the sixth of his career and improved dramatically after allowing Cleveland five runs in four innings last Saturday.
He walked two batters in the fourth and threw a wild pitch before giving up an RBI single to Manny Machado for Baltimore's only run.
Baltimore starter Jason Hammel (7-4) gave up only three hits through six innings, but he surrendered a leadoff single to James Loney in the seventh and Jennings then hit the first pitch he saw over the wall in center.
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