CHICAGO - Don't ask Justin Ruggiano about his achievements, ask him about teammate Junior Lake.

Ruggiano's two-out, two-run double in the seventh inning provided the margin of victory in the Chicago Cubs' 5-3 victory over the Washington Nationals on Thursday night. Yet the outfielder seemed more interested in talking about Lake.

While Lake left in the second inning and had no effect on the outcome, he definitely had an impact — literally and figuratively — with a mad dash in centre field after a ball and a hard slide into a metal door built into the brick outfield wall at Wrigley Field.

"He hit that thing really hard," said right fielder Ruggiano, who also went after the ball off the bat of Ryan Zimmerman, but wisely pulled up. "I don't think he slowed down at all. He wasn't moving at first and that was kind of scary, and then he was responding and that was good.

"Then all of a sudden, it was like he came to and he wanted to play. At that point, I was just like, 'Let's wait for the doctor to get out here.' "

Although Lake left the game, the Cubs reported his only injuries were bruises, one on his head and one on his knee.

"He went after that ball pretty hard," Cubs manager Rick Renteria said. "I mean, you couldn't give a better effort than that. I know he went into that slide, but he still ended up hitting the whole left side (of his body)."

Besides Ruggiano's heroics — he went 2 for 4 and also had a run scored — Starlin Castro had two RBIs and Anthony Rizzo went 3 for 4 with two doubles and a run scored.

The Cubs had dropped four of five games before the win in cold conditions with a dense fog blowing in off Lake Michigan.

Denard Span went 2 for 4 with two doubles and two RBIs for the Nationals, but was involved in the second-most bizarre play when he lost a fly ball in the fog.

"Just rough conditions," he said. "Nothing you can do to prepare for that. I don't think I've ever played in a game with that much fog. You just try to concentrate and try to keep your eye on the ball as long as possible and hope that you can kind of gauge where the ball is going to be once it's hit."

Neither starter was involved in the decision. The Cubs' Travis Wood gave up three runs on seven hits in 6 2/3 innings and was hurt most by five walks. Washington's Doug Fister also allowed three runs on seven hits.

Cubs reliever Neil Ramirez (1-1) got the win and Hector Rondon pitched a perfect ninth for his ninth save.

The Cubs opened the scoring with three runs in the fourth by bunching hits. Ruggiano's lead-off grounder surprisingly was scored a hit when third baseman Anthony Rendon threw well wide of first.

Rizzo followed with a double. Castro, who took over the team lead in RBIs on Wednesday, added to his total with a two-run single. One out later, Welington Castillo singled to drive in Castro.

Washington finally pushed across a run in the sixth. Span led off with a double and Rendon immediately drove him in with a single.

The Nats rallied in the seventh as Wood started the inning with back-to-back walks and, following a sacrifice bunt, two runs scored on a double by Span to tie the score at 3.

"I had some walks kind of in the first couple of innings, spaced out, nothing too big," Wood said. "But to walk two there in the seventh can't happen. Once again, walks end up hurting me tonight."

The Cubs staged their rally in the bottom of the inning and took the 5-3 lead on Ruggiano's double off reliever Craig Stammen (0-3).

"It was nice to help out," Ruggiano said. "You always feel like hitting in front of Rizzo you're going to get pitches to hit."

NOTES: Nats OF Bryce Harper (torn ligament left thumb) is on a rehab assignment at Double A Harrisburg and could be activated Monday if all goes well. "When he comes back we want him to feel good at the plate, feel good in the field and have his legs underneath him full go," manager Matt Williams said. "We don't know how the next three or four days will go, but he's well on his way." ... Cubs manager Rick Renteria said he won't start catcher Castillo (rib cage inflammation) every day initially now that he's back from the DL. ... The Nats activated C Wilson Ramos (strained right hamstring). . RHP Tanner Roark (7-4) faces Jason Hammel (6-5) in the second game of the four-game series.