For the first time in their two years as teammates, Zimmerman and Dunn were both held out of the lineup Thursday. Still, the Nationals responded with three home runs and their third consecutive win.
Michael Morse homered, doubled and drove in three runs, Roger Bernadina and Danny Espinosa each hit a two-run shot and Ross Detwiler earned his first win in nearly a year as Washington beat the Houston Astros 7-2.
Zimmerman and Dunn have missed a combined 15 games this season and eight in 2009.
"Let those guys rest. They've played every day. They're horses," Morse said. "Zim -- he's like Cal Ripken out there. You can't get him out of the game. It was good to get them the rest."
Zimmerman will probably be out of the lineup for a few days with a strained intercostal muscle. Washington manager Jim Riggleman said he expected Dunn, who has a sore elbow and hamstring, to be back Friday.
Morse was inserted in the cleanup spot and extended his tear at the plate. In his last 24 games, he is batting .366.
"That's what we expect. That's what they expect from themselves," Zimmerman said. "Today showed what kind of depth we have, what kind of team we can have moving forward."
The Nationals have won three straight at home for the first time since July 29-31.
Earlier in the day, Nationals president Stan Kasten announced his resignation after 4½ seasons with the club. He said he'd told team ownership about a year ago that he'd be leaving.
Zimmerman probably had more interaction with Kasten than any other Washington player and said he'd miss him.
"He's been around sports a long, long time. He's seen everything. He's done everything," Zimmerman said.
Detwiler (1-2) pitched six innings, allowing two runs and seven hits. He walked two, did not strike out a batter and hit one with a pitch.
It was his first win since Sept. 28, 2009. He missed much of the season after right hip surgery in February.
"There were four shortstops out there," Detwiler said. "I can induce contact and know there's going to be an out made."
Morse led off the second with his 13th home run.
Washington scored four times in the sixth off Nelson Figueroa (5-4) when Morse hit a two-run double and Bernadina hit his 11th homer of the year. Morse has five hits in six at-bats against Figueroa.
"That's enough for you to not want to pitch to a guy like that," Figueroa said. "I was cruising along there for a little while and just ran into a rut."
Espinosa hit his sixth homer, a two-run shot, his second in as many days, in the seventh.
Jeff Keppinger had three hits for Houston, losers of three in a row for the first time since early August.
The Astros scored in the first when Jason Bourgeois led off with a single, stole second and Keppinger doubled.
A single by Keppinger set up Hunter Pence's infield hit for Houston's other run in the fifth.
Pence returned to the lineup after missing two games with a right hip flexor. ... Houston OF Michael Bourn missed his fifth game with a strained right oblique. ... Keppinger played his 40th consecutive errorless game at 2B. ... Atlanta RHP Tim Hudson will pitch against Washington on Friday night. He's 10-1 with a 1.49 ERA when facing the Nationals.