Ryan Zimmerman exchanges a high-five with Jayson Werth after the Nationals’ rally. (Ann Heisenfelt/Associated Press)

Over a week ago, sitting before a throng of reporters in the modest and messy media room of the low Class A Hagerstown Suns, Ryan Zimmerman detailed the progress of his two-month-long rehabilitation from a frustrating abdominal muscle tear that, because of its reluctance to improve since its injury on April 9, needed surgery to remedy.

For a player of his caliber, among the best at his position in the league and the best on his major league team, the experience was somewhat humbling, having to rebuild his strength and play at that level of the minor leagues for the first time since his rookie season in 2005. But then, Zimmerman spoke with a slight grin about his hopeful return to his major league teammates and how he hoped to help them win.

In many ways, Zimmerman’s return from the disabled list to Nationals Park on Tuesday brought what teammates billed as an immediate “shot in the arm” — energized cheers from the crowd and thoughtful presence in the clubhouse. But it was also Zimmerman’s bat, after working through some initial rust, that helped spark a six-run seventh-inning rally with a double and led to an 8-6 win over the St. Louis Cardinals.

Zimmerman’s slicing double that barely fell inside the right field line scored Jayson Werth. With Werth reaching on a walk and Ian Desmond reaching on an infield single, this was exactly the type of hitting with runners on base that the Nationals had hoped Zimmerman’s bat would create. And then, the hitting became contagious.

“I can’t even remember all the at-bats, there were so many good at-bats,” Manager Jim Riggleman said. “We got a couple breaks, a couple hits that weren’t really squared up that well. But a couple big ones.”

The Nationals sent 12 batters to the plate that inning, totaled five hits, scored six runs and took their first and only lead of the game. A bases-loaded wild pitch to pinch hitter Ivan Rodriguez scored the game-tying run. Pinch hitter Laynce Nix’s 10-pitch, bases-loaded walk then scored the go-ahead run. And Werth’s single to right added the eighth and final run — a much-needed exclamation point for an offense that has been struggling and a hitter batting .236 with a huge offseason contract.

Zimmerman, who missed 58 games this season, finished 1 for 5, striking out twice and stranding three base runners. Though the well-regarded player was referred to by teammates as a “game-changer,” Zimmerman played down his role as the savior to an offense that has scored three runs or less in seven of the past 10 games and ranks last in the National League in team batting average.

There were immediate signs of Zimmerman’s impact. With his first defensive play of the game, a ground ball by right fielder Andrew Brown in the second inning, Zimmerman elicited cheers from the 26,739 in attendance.

After his best pitching performance since he signed with the Nationals from Cuba last July, a strong and promising six-inning outing against the San Francisco Giants last week, starter Yunesky Maya struggled. He yielded a single to the game’s first hitter, Ryan Theriot, and then gave up a rocket home run to left field to Albert Pujols on the second pitch of the at-bat. And so, within three batters, the Nationals were already playing from a 2-0 deficit.

It further unraveled for Maya, who has yet to win a major league start, in the fourth inning when he allowed a home run on the first pitch of the inning to Lance Berkman. And it continued an inning later when Maya allowed consecutive hits, a single to Theriot and double to Colby Rasmus. A single by catcher Yadier Molina scored Berkman, who had reached on a fielder’s choice, for a 6-1 lead.

Despite the return of Zimmerman, the Nationals have been dealing with nagging injuries to a handful of players. Roger Bernadina, who likely would not have started against Cardinals left-handed starter Jaime Garcia, had been kept out of Sunday’s game because of tightness in his left hamstring but was forced into action in the second inning when Rick Ankiel was pulled because of a strained left intercostal muscle, essentially his ribs.

So it was only fitting in this night of returns from injuries that Bernadina come up to bat in a key spot for the trailing Nationals. With the bases loaded with no outs against Garcia in the sixth inning, Bernadina hit a weak groundball to right side that resulted in a double play.

Behind a strong 11/ 3 innings from Ryan Mattheus in his major leagueappearance and a solid inning from Henry Rodriguez, the Nationals held down the Cardinals’ offense and set the stage for the rally in the seventh, which started with Werth’s walk, featured a hit by Zimmerman and an offense that came to life around him.

Zimmerman “looked fine,” Riggleman said. “I thought he had some good swings, some good takes. . . . It’s been a while, it’s major league pitching, but just to come in and get comfortable, it’s big. I think as we go through, we’ll feel his impact in the lineup.”