CHICAGO -- It almost doesn't matter who Joe Maddon calls on to start or sub these days, the Chicago Cubs just keep on winning.

The Cubs improved to 23-6 -- their best 29-game start since 1907 -- with Saturday's 8-5 victory over the Washington Nationals.

"The vibe within the group is outstanding," the Cubs manager said. "They're ready to play every day, they're playing loosely and they're playing focused and there's a lot of confidence.

"My job is to continue to nurture that."

The victory was Chicago's sixth straight and third in the current Nationals series as the Cubs clinched their eighth series win in nine this season.

Addison Russell dropped a bases-loaded double down the right-field line for two go-ahead runs to break a 5-5 tie in the seventh inning of a see-saw game.

Russell sent reliever Shawn Kelley's 2-2 pitch to right to score Kris Bryant and Anthony Rizzo for a 7-5 lead.

"All I want to do is come through," Russell said. "It just happened so quick. I thought the ball was going to be foul."

The Nationals (19-11) suffered their third straight loss -- all to Chicago -- but still have the National League's second best record.

Washington manager Dusty Baker was matter-of-fact about his team's struggles and how well the Cubs have performed.

"The ball didn't bounce our way," Baker said. "They're getting everything that they need over there and everything that they want."

Neither Nationals starter Gio Gonzalez nor Cubs starter Jason Hammel figured in decisions.

Adam Warren (3-0) -- the fifth of seven Cubs pitchers -- earned the win after facing three batters in the seventh. Hector Rondon worked a perfect ninth for his sixth save.

Left-hander Sammy Solis, the third of five Washington hurlers, fell to 0-1 after giving up two runs on two hits in 2/3 of an inning.

The Cubs added another run in the eighth as Ben Zobrist's one-out single scored Fowler from third after they loaded the bases on Nationals reliever Felipe Rivero.

Russell went 2-for-3 with a walk, one run scored and three RBIs. Dexter Fowler and Rizzo also had two hits for the Cubs. Ben Revere and Stephen Drew each had two hits for the Nationals.

Washington opened the scoring after Revere doubled to lead off the third, reached third base on a sacrifice grounder and scored on Bryce Harper's sacrifice fly to deep right.

Chicago quickly replied as Tim Federowicz singled to left with one out, was sacrificed to second and came home as Fowler lined a triple to left-center -- his second of the season -- to even the score.

Bryant shook out of a 1-for-8 homestand slump with a fourth-inning leadoff home run. Bryant's fifth homer of the season -- a solo shot -- came on an 0-2 pitch from Gonzalez and gave the Cubs a 2-1 lead.

The Nationals forced a 2-2 tie in the fifth as Jose Lobaton led off with a walk, advanced on back-to-back sacrifice grounders and scored when Danny Espinosa dribbled a grounder just past Cubs second baseman Ben Zobrist.

Espinosa reached second as Harper walked and later scored to make it 3-2 on Ryan Zimmerman's hit to center.

Hammel departed after five innings and 97 pitches, allowing three runs on four hits while walking four and striking out three.

Washington made it 4-2 in the sixth when Drew doubled home Anthony Rendon off Cubs right-handed reliever Spencer Patton with none out. But Chicago escaped any more damage when Gonzalez later grounded into an inning-ending double play.

Chicago scored three runs after two were out in the bottom of the inning.

Russell's two-out hit to center drove in Rizzo from third for the first run and spelled the end for Gonzalez, who departed for right-hander Blake Treinen.

Treinen walked pinch hitter Tommy La Stella to load the bases. Solis then entered and gave up a two-run single to pinch hitter Ryan Kalish as Jorge Soler and Russell scored for a 5-4 Cubs lead.

Gonzalez finished with an even 100 pitches while allowing five runs on seven hits. He walked one and struck out a pair.

Revere, just off the disabled list this week, led off the seventh with a triple to the right-field corner and scored for a 5-5 tie on Zimmerman's fielder's choice grounder to third.

"Ben looked like Ben Revere today -- he got a double and a triple," Baker said. "That's a big positive."

NOTES: Nationals 2B Daniel Murphy wasn't in Saturday's starting lineup after collecting his second four-hit game in three days in Friday's 8-6 loss to the Cubs. He pinch-hit in the ninth with a fly out. ... The National's 19-10 record through 29 games was the best start by the current franchise and fourth best by any D.C.-based team. Washington Senators' teams in 1925, 1930 and 1932 started 20-9. ... Following Sunday's series finale, the Nationals return home to open a three-game series on Monday against Detroit. ... Saturday's game was just the Cubs' 13th at home, tied for fewest in the major leagues with Cleveland and Detroit. ... Cubs RHP Jake Arrieta (6-0, 0.84 ERA) goes for a major league-leading seventh victory in Sunday's series finale against Nationals RHP Tanner Roark (2-2, 2.35). ... The Cubs remain home, opening a three-game series against San Diego on Monday.