CHICAGO -- The light fog that blanketed Wrigley Field on Thursday didn't seem to affect Justin Ruggiano's view from the plate.
The Cubs center fielder went 2-for-4 and doubled in a pair of go-ahead runs in the seventh inning as Chicago beat the Washington Nationals 5-3 in the opener of a four-game series.
"The fog was tough," said Ruggiano, whose hit off National's reliever Craig Stammen (0-3) broke a 3-3 tie. "The only thing I can compare it to was a snow game (in Triple-A) where the ball went up and I don't think anyone ever saw where it landed.
"(But) it was nice to help out. You always feel like hitting in front of (Anthony) Rizzo you're going to get pitches to hit. ... And as a two-hole hitter I think it's your responsibility to be looking (for) good pitches."
The game had some scary moments in the second inning as Cubs outfielder Junior Lake crashed into a door while chasing a deep fly ball.
Lake hit the side of his head and knee and suffered a contusion. He left the game unaided and suffered no concussion symptoms according to a post-game report.
"He hit that thing really hard," said Ruggiano who started the game next to Lake in right. "I don't think he slowed down on it at all. He wasn't moving at first and that was kind of scary. Then I started talking to him and he was responding."
Ruggiano's game-winning hit came off Nationals reliever Craig Stammen (0-3) and broke a 3-3 tie.
Cubs reliever Neil Ramirez (1-1) worked 1/3 of an inning in the seventh for the victory and closer Hector Rondon worked a 1-2-3 ninth for his ninth save of the season.
Cubs first baseman Anthony Rizzo was 3-for-4 with a run scored. Nationals catcher Wilson Ramos -- in his first game back from the disabled list -- and center fielder Denard Span each had two hits.
The loss was Washington's second straight. Chicago won for only the second time in six games.
The Cubs (33-44) built a 3-0 lead while starter Travis Wood sailed through five scoreless innings before the Nationals (41-37) tagged him for their first run.
Span led off the sixth inning with a double and scored on third baseman Anthony Rendon's single to right to trim the Chicago lead to 3-1.
Cubs third baseman Luis Valbuena tripled to center with two outs in the sixth but was stranded when catcher Welington Castillo flied out to center.
In the seventh, Span launched a two-run double to the right field corner, scoring Ramos and second baseman Danny Espinosa to tie the score 3-3. Span was thrown out at second.
That was all for Wood, who worked 6 2/3 innings and allowed three earned runs and seven hits, walked five and struck out four.
"It turned into (a grind), walks through the first couple of innings, I spaced out," Wood said. "To walk two there in the seventh you can't have that. Walks ended up hurting me again tonight."
Nationals starter Doug Fister did not return for the seventh, working six innings and giving up three earned runs and seven hits while striking out just one.
"We battled back," Nationals manager Matt Williams said. "We find ourselves in that position a lot where if we are down early we have a chances to come back. But it didn't work out tonight."
The Cubs reclaimed the lead in the seventh against Stammen as Ruggiano tripled down the left field line with two outs, scoring second baseman Darwin Barney and left fielder Ryan Sweeney to open a 5-3 lead.
Nationals left fielder Ryan Zimmerman led off the second inning with a double to deep right center, a play that saw Lake injured with running for a catch. Zimmerman, meanwhile, later tried to score on Ramos' single to left but was thrown out at home on a tag by Castillo.
Ramos was playing in his first game since June 10. He was activated off the disabled list (strained right hamstring) earlier Thursday and inserted in the lineup against the Cubs.
Cubs shortstop Starlin Castro lined a short single to left with none out in the fourth to score Ruggiano from third and Rizzo from second for a 2-0 Cubs lead.
Castro moved to second on a wild pitch and came home on Castillo's base hit to center to make it 3-0.
NOTES: Washington activated C Wilson Ramos from the disabled list and optioned C Sandy Leon to Triple-A Syracuse. Ramos missed the minimum 15 days with a strained right hamstring. ... The Nationals and Cubs will become quite familiar with each other during the next 11 days. In addition to four consecutive games in Chicago -- including a Saturday doubleheader and a rare Sunday off -- the teams meet three times in Washington on July 4-6. ... The Nationals send RHP Tanner Roark (7-4, 2.79 ERA) against Cubs RHP Jason Hammel (6-5, 2.99 ERA) on Friday in the second game of the series. ... The Cubs faced a right-hander (Doug Fister) for the 15th consecutive game Thursday, and they are due to face another Friday before Nationals LHP Gio Gonzalez is scheduled to start the opener of Saturday's day-night doubleheader.