The exhilaration of the Washington Nationalsfirst division crown still coursed through Nationals Park on Tuesday night. The clubhouse had a faint day-after smell of champagne, beer and wet carpet. Fans cheered at the introduction of their “National League East champion Washington Nationals.” This city’s long-awaited playoff appearance was nearly set.

Save one important factor: who the Nationals would play. Entering their penultimate regular season game, the Nationals had a vague idea of which team they would face in their National League Divisional Series. They had four potential opponents. And with Tuesday night’s 4-2 win over the Philadelphia Phillies using mostly backup players, the Nationals shed only a little more light on the uncertainty.

With the win, Nationals trimmed their magic number to claim the top seed in the National League to one. But the Cincinnati Reds’ 3-1 win over the St. Louis Cardinals kept them tied with the Nationals for the league’s best record. The Nationals, who hold the tiebreaker because they won the season series against the Reds, control their own fate. Win the regular season finale on Wednesday and Washington would begin the city’s first playoff series since 1933 as the top seed. Lose and they could be the second seed, unless the Reds lose, too.

Nationals Manager Davey Johnson was concerned enough about seeding to skip Tuesday’s scheduled starter, Gio Gonzalez, and give left-handed long reliever Tom Gorzelanny his first start since July 2011. In doing so, Johnson avoided the possibility of Gonzalez starting the playoff opener on Saturday on short rest should the Nationals fall behind the Reds. But after Tuesday’s game he said he cared little about earning the NL’s top regular season record.

“I don’t know how it’s that important,” he said. “You’ve got to beat the teams you play. The only nice thing is we don’t have to fly cross-country [in the divisional series]. That’s the only nice thing. The pitching’s set up for whoever we play. The kind of year we’ve had, it would be fitting to finish it off with the best record. And more importantly, I’d like to see [Wednesday’s starter Edwin] Jackson get his 10th win. That’s a little higher up on the list than best record.”

With one more win, the Nationals would face the winner of Friday’s one-game wild-card playoff between the Atlanta Braves and Cardinals. Even if the Nationals lose their 1 p.m. game on Wednesday, a Reds loss would still hand them the top seed. It took 160 games for the Nationals to claim the NL East crown. It will take one more game to determine whom they will face next.

In addition to resting Gonzalez, Johnson filled Tuesday’s lineup card with six backup position players. Johnson wasn’t necessarily conceding the top seed, but said he wanted to reward his regular starters with a day off. Many of the players on the field, such as Steve Lombardozzi, Roger Bernadina and Tyler Moore, were regular players this season while established starters were injured. Still, with the rarely used, 37-year-old Mark DeRosa starting at shortstop for the first time in six years, it felt a little like a meaningless October game.

“How about that Goon Squad?” Johnson said, referring to his bench players by their collective nickname. “Told you they were tough.”

Two Nationals regulars, Bryce Harper and Adam LaRoche, remained in the lineup against Phillies spot starter B.J. Rosenberg. Johnson originally scheduled both players to rest Tuesday, but both lobbied to play. LaRoche entered the game one RBI short of 100 on the season. “If I had finished on 99, it would have been a tough pill to swallow,” LaRoche said.

LaRoche reached the milestone for the second time in his career — and became only the third Nationals player to do so — with a solo home run to right field in the sixth inning off reliever Josh Lindblom. The crowd continued cheering after LaRoche retreated to the dugout, drawing him out for a curtain call. The power-hitting mainstay of the Nationals’ lineup stood on the top step and tipped his helmet. The blast gave the Nationals a 2-1 lead.

Lombardozzi added to the cushion with an RBI single to center field later in the inning. Gorzelanny filled in well, striking out five batters and allowing only one run over 3 2/3 innings. The Nationals’ bullpen didn’t allow a run until Tyler Clippard surrendered a solo home run in the eighth to rookie Darin Ruf, his second of the game.

The Nationals added an insurance run in the eighth inning, one started by a DeRosa double that smashed off the center field wall, just short of his first home run of the season. DeRosa, beloved by his teammates, has endured a trying season filled with injuries and the death of his father. A home run, he said, would have meant a lot to him.

Teammates “were begging for it to go out, too,” DeRosa said. “I mean, I’m there every day, top step, for them, too, so I appreciate it.”

Later in the inning, Lombardozzi’s sacrifice fly scored Bernadina, who slid in under Erik Kratz’s tag for a 4-2 lead. Drew Storen pitched a quick ninth to notch the save.

For the Nationals, there’s no decided advantage to securing the NL’s top seed. As either of the top two seeds, the Nationals would begin the divisional series on the road because of a scheduling quirk in the playoff schedule. The addition of the one-game wild-card playoff means the Nationals, if they earn the top seed, would have less than 48 hours to travel to face their opponent once they learn who it is.

Some of the players said they shared Johnson’s feelings on the matter. It showed after the win, as most of the televisions in the clubhouse showed the New York Yankees-Boston Red Sox game and not the Reds-Cardinals game. They didn’t mind having to wait another game until they could continue their magical run into the postseason.

“I think we’re 50-50 on it,” LaRoche said. “I don’t know necessarily the advantage. We’re going to play to win tomorrow and either way we’re not in a bad spot. So I’d say we’re fine, whatever happens.”