WASHINGTON -- Welington Castillo got his bat on the ball at precisely the right time.
Even though it was a complete accident and Castillo didn't get credit for a hit, his bat essentially won the game for the Chicago Cubs.
Alfonso Soriano scored the tiebreaking run in the ninth inning after a one-of-a-kind throw by Washington catcher Kurt Suzuki went for an error, and the Cubs rallied to beat the Nationals 2-1 Sunday.
The Cubs didn't have a baserunner through the first five innings and trailed 1-0 entering the eighth before coming back in the deciding matchup of a three-game series.
Facing Nationals closer Rafael Soriano (0-1) in the ninth, Alfonso Soriano singled and took second on a single by Julio Borbon. After Ryan Sweeney struck out, both runners took off on a double steal with Castillo at the plate.
Suzuki's throw hit Castillo's bat. The ball veered well to the left of third base and into foul ground, allowing Alfonso Soriano to scoot home.
"I was just standing there and I just feel the ball hitting my bat and the ball fly into the outfield," Castillo said.
If Castillo moved into the throw, interference would have been called.
"I didn't move. I just looked," Castillo said. "Only thing that I say when (Suzuki) said something to the umpire is, 'I didn't move.' And the umpire said, 'I see you didn't move."'
Cubs manager Dale Sveum said, "The way you draw it up, that's the way you do it. Make the catcher get around you. Don't let him have the throwing lane."
Suzuki shrugged his shoulders afterward and said, "That's the first time I have ever done something like that, let alone saw it. It's one of those things, where a freak thing happens like that."
Alfonso Soriano concluded: "It's a huge play for us and we score a run and we don't have to hit the ball."
James Russell (1-0) worked the eighth and Kevin Gregg got three outs for his sixth save.
"A very big win for us," Alfonso Soriano said.
The Cubs won the final two games of the series, even though the Nationals started Stephen Strasburg and Gio Gonzalez.
"To come back and win both games obviously against the two best pitchers in baseball showed me a lot about these guys," Sveum said.
Ryan Zimmerman drove in the run for the Nationals, who went 1 for 9 with runners in scoring position. After missing the first two games of the series with an ingrown toenail, Washington's Bryce Harper went 0 for 2 with two walks and is mired in 4-for-35 skid.
Nationals starter Gio Gonzalez retired the first 15 batters he faced, finished with seven innings of two-hit ball and left with a 1-0 lead. But the bullpen couldn't make the advantage stand up.
"I feel like we have a great bullpen," said Gonzalez, who was pulled after throwing only 86 pitches. "You turn the page, move forward and go to the next series."
Gonzalez walked one and struck out six. He was flawless until Dioner Navarro opened the sixth by beating out a grounder deep in the hole that shortstop Ian Desmond gloved before opting not to attempt a throw.
The Cubs then used a walk and a single to load the bases with two outs before Gonzalez retired Anthony Rizzo on a grounder to first base.
Gonzalez concluded his performance with a perfect seventh.
In the eighth, however, Chicago pulled even against reliever Drew Storen. Navarro drew a leadoff walk and was replaced by pinch-runner Travis Wood, who advanced on a sacrifice and scored on a two-out single by Starlin Castro.
Cubs starter Scott Feldman gave up one run, five hits and three walks in six innings.
The Nationals hit two doubles and drew two walks in the first inning, but they left the bases loaded after Zimmerman doubled in a run.
Washington also stranded a runner in scoring position in the second and third innings. By that time, Feldman's pitch count was at 61.
NOTES: Cubs 3B Luis Valbuena, who jammed his right pinky finger Saturday, was available to pinch hit but did not play. ... The Montreal/Washington franchise missed a chance to earn its 300th win against the Cubs. The teams next meet in Chicago for a four-game series August 19-22. ... After going 3-2 on their homestand against Detroit and Chicago, the Nationals begin a West Coast trip Monday night with Jordan Zimmerman (6-1) on the mound against the Dodgers. ... Travis Wood (3-2) will start for the Cubs on Monday night in the opener of a three-game home series against Colorado.