Laynce Nix added a pair of insurance runs with an RBI single after Zimmerman’s hit in the ninth.
Danny Espinosa. Zimmerman’s grounder rolled just out of reach of a diving Jeff Keppinger and into the outfield to allow Bernadina to score and chase Houston starter Jordan Lyles (0-5).
The Astros’ rookie allowed five hits and four runs with six strikeouts in the longest outing of his career to remain winless in ninth career start.
Morse homered in the fifth inning and Zimmerman’s came in the seventh.
Washington starter Jason Marquis (8-4) yielded six hits and two runs with a season high-tying nine strikeouts to get his first win since June 10.
Michael Bourn singled to start Houston’s side of the eighth, but Marquis retired the next three Astros to end the inning and his night.
Closer Drew Storen allowed one hit in a scoreless ninth for his 25th save.
Lyles had retired seven straight before Zimmerman’s homer that landed in the first row of the stands in right field with one out in the seventh inning and tied it 2-all. Morse followed with a single, but Lyles retired the next two Nationals to get out of the inning before pitching a perfect eighth.
Carlos Lee’s two-out double down the left field line scored Angel Sanchez and gave the Astros a 2-1 lead in the sixth inning.
Lyles didn’t allow a hit until Morse’s homer to left field on the first pitch of the fifth inning. He walked Bernadina to start the fourth inning, but faced the minimum through four thanks to a double play in that frame.
The Astros evened it at 1-all when Jason Michaels doubled and scored on a double down the right field line by Carlos Corporan in the fifth inning.
The first hit Marquis yielded was a single by Corporan with no outs in the third inning. He retired the next six Astros after that before the double by Michaels in the fifth inning.
Nationals infielder Jerry Hairston Jr., who had a broken bone in his right wrist, was activated from the disabled list on Monday, but did not play.
NOTES: Buddy Lamothe, the Astros’ 40th-round pick in this year’s draft who is paralyzed from the waist down, was on the field with the team for batting practice before Monday’s game. The Astros had their eye on the reliever from San Jacinto College before he was injured in a diving accident in May. Lamothe, who is recovering at a facility in Houston, hopes to play again one day. “Being out here just gives me a lot of hope to get back out here one day and pitch for the Astros,” he said while on the field with his family and college coaches. “That’d be nice.”... C Ivan Rodriguez (strained right oblique) is feeling better, but Nationals manager Davey Johnson still isn’t sure when he’ll come off the disabled list. ... The Nationals hope that starter Tom Gorzelanny will be able to make his next scheduled start after twisting his right ankle on Sunday in a home-plate collision. If he isn’t, the Nationals could go with four pitchers in their rotation for a bit because of two upcoming off days. ... Houston OF Jason Bourgeois (right quadriceps strain) went 0 for 5 in a rehabilitation start at Double-A Corpus Christi on Sunday. He will join Triple-A Oklahoma City on Tuesday. ... Houston INF Matt Downs, who is on the paternity leave list, and his wife Leah welcomed their first child, a boy named Matthew Jr. on Monday.