Rendon, a third baseman, is getting a good look by the Nats, though he'll likely need more seasoning before attaching to the big club. His only AA experience was 21 games in the Eastern League in 2012.
Washington improved to 8-8 with the win, while Houston dropped to 7-9.
San Francisco improved to 7-8 with a 9-5 road win over Cincinnati, getting a 3-for-4 effort from catching prospect Johnny Monell.
Monell delivered a pair of doubles and a single, driving in three runs and scoring three times in four at-bats for the Giants, boosting his average to a stratospheric .600 (9-for-15).
After playing a full season of AA ball with Richmond in the Eastern League, Monell is being scrutinized by San Francisco coaches this Spring but has not made the official roster.