Gonzalez originally was slated to start Tuesday night against the Philadelphia Phillies, if the next-to-last game of the regular season still mattered for the division title.
But with that championship wrapped up Monday, Johnson decided to make sure Gonzalez, who is 21-8 with a 2.89 ERA, is fresh for Washington's NL division series opener.
The Nationals still don't know which team they'll face to begin the postseason or which day they'll open play. It could be Saturday (in which case Gonzalez would only have had three days' rest had he pitched Tuesday against Philadelphia) or Sunday.
"I know that they have high hopes for me, and it's one of those things where you take it as an honor. They've got something planned for me, and I want to go out there and try to show this team that I'm going to go out there and try to do the best I can," Gonzalez said. "I want to get enough rest, but not too much."
Another lefty, reliever Tom Gorzelanny, was picked by Johnson to start Tuesday's game instead and was expected to go about three or four innings before turning it over to other members of the bullpen. A marker-on-paper sign hanging in Gorzelanny's locker in the Nationals Park clubhouse before the game read: "Game (hash)161 is my game!"
Center fielder Bryce Harper and first baseman Adam LaRoche were the only everyday players in Tuesday's starting lineup, with Johnson opting to sit third baseman Ryan Zimmerman, right fielder Jayson Werth, left fielder Michael Morse, shortstop Ian Desmond, second baseman Danny Espinosa and catcher Kurt Suzuki.
Not necessarily the best way to try to earn the top seeding for the playoffs for a Nationals club that entered Tuesday with the same best-in-baseball record (96-64) as the NL Central champion Cincinnati Reds.
"I'm rewarding the guys that have been grinding through a tough schedule. ... Set back, gather your thoughts, we'll get back up tomorrow, and go from there," Johnson said. "Listen, I have all the confidence in the world in the guys I've got out there. Those guys have been regulars."
Among the members of the makeshift lineup was Mark DeRosa, getting his first start at shortstop since Sept. 2, 2006, when he was with the Texas Rangers. It's the sixth position he's played this season for Washington.
Harper was chosen NL Rookie of the Month for September. He led the majors with 26 runs while slugging .651 with 69 total bases, including seven homers, seven doubles, three triples and 14 RBIs. Harper also won the monthly honor in May.