ST. LOUIS - Before stepping foot on the field at Busch Stadium for their full team workout, the Nationals finalized their roster for the National League Division Series.

The roster hasn’t been filed with the league office, so it’s not official as of yet. Manager Davey Johnson commented - perhaps half-seriously and half-jokingly - that since the Nats hadn’t seen the Cardinals’ roster yet, they weren’t going to announce theirs.

Johnson has, however, informed all of his players about their role for this series with the Cardinals.

There are no surprises among the 25 guys on the roster. The Nats will go with four starters (Gio Gonzalez, Jordan Zimmermann, Edwin Jackson and Ross Detwiler), eight relievers (Drew Storen, Tyler Clippard, Sean Burnett, Ryan Mattheus, Craig Stammen, Michael Gonzalez, Tom Gorzelanny and Christian Garcia) and 13 position players (Adam LaRoche, Danny Espinosa, Ian Desmond, Ryan Zimmerman, Michael Morse, Bryce Harper, Jayson Werth, Kurt Suzuki, Jesus Flores, Steve Lombardozzi, Chad Tracy, Tyler Moore and Roger Bernadina).

That leaves left-hander John Lannan and infielder Mark DeRosa as observers. Both guys are with the team here in St. Louis, as are Stephen Strasburg, Zach Duke, Chien-Ming Wang and injured catcher Wilson Ramos.

The Nats sent a handful of position players down to their minor league complex in Viera, Fla., to stay loose, including catcher Sandy Leon and outfielders Corey Brown and Eury Perez.

If there’s an injury to one of the guys on the Nationals’ postseason roster, those ones in Florida will be in shape and ready.

We knew that the Nats would go with Gonzalez in Game 1 and Zimmermann in Game 2, but Johnson said today he’s decided to go with Jackson for Game 3 on Wednesday, and Detwiler as his Game 4 starter (if necessary) Thursday.

Johnson said that would have likely been the way the rotation lined up even if the Nats had faced the Braves, a team which has more success against left-handed starters than righties, in the NLDS.

“I kind of like the experience that Edwin Jackson brings,” Johnson said, ” So I probably, even if it had been Atlanta, I would have probably gone with Jackson (for Game 3).”

Here’s how Cardinals manager Mike Matheny will line up his rotation for this series: Adam Wainwright will go Game 1, Jaime Garcia will pitch Game 2 and Chris Carpenter is in line to start Game 3. After that, Matheny could go back to Kyle Lohse, who got the win yesterday in the wild card win over the Braves, and Wainwright would be in line to pitch Game 5.

On a separate topic, Johnson says he feels a lot better after needing to leave the Nationals’ regular season finale due to a nerve issue in his lower back. Left fielder Michael Morse, who Johnson reported suffered a bit of a hamstring cramp during Wednesday’s game, is “good to go,” Johnson said.