"He hit that thing really hard," Ruggiano said of the Cubs center fielder, who crashed into the wall in the second inning trying to catch Ryan Zimmerman's fly ball. "There's not really a safe place to hit out there. You guys just happened to be able to hear that one because it was a metal door. I'm pretty sure everyone in the stadium heard that."
Lake was able to walk off under his own power, and sustained bruises on his head and left leg, but no concussion symptoms, the Cubs said. He went full-force into the door.
Zimmerman led off the Nationals' second with a double into the gap in right-center that Lake sprinted after. But the outfielder didn't get the ball or have time to avoid the wall, and slid into the wall, slamming his head and left leg into the metal door and brick base. It's one of the few spots where there is no ivy, although that does not provide much padding.
Lake stayed on the ground on the warning track, and Cubs athletic trainers PJ Mainville and Ed Halbur plus team physician Dr. Stephen Adams and Cubs manager Rick Renteria went out to check on the outfielder. Cubs shortstop Starlin Castro also was there, and after Lake sat up, he and the shortstop were laughing.
"He wasn't moving at first, and that was kind of scary," said Ruggiano, who was playing in right field. "Then I started talking to him and he was responding, so that was good. All of a sudden, it was like he came to and wanted to play. At that point, I was like, 'Hey, just wait for 'Doc' to get out here to look him over."
Lake will be re-evaluated on Friday.
"It seems like he survived it," Renteria said. "He couldn't have given a better effort than that. He went into that slide, but still ended up hitting the whole left side pretty good."
Castro said he thought Lake had broken something because of the impact.
"He said he didn't have anything hurt," Castro said. "When he got up, they asked if it hurt, and he said, 'No.' He was good, he walked good, he wanted to play, but they didn't let him."
After the inning was over, Castro went into the clubhouse to check on his teammate and countryman, and Lake was watching a replay of the collision.
"Wow, that was scary," Castro said.
Lake didn't talk to the media after the game, but was seen laughing and eating sushi with his teammates. He's an aggressive player, and also new to the outfield, having converted full-time last year. Castro said he's tried to warn him about avoiding collisions.
Castro's advice: "I said, 'Hey, you're not in the Dominican. They've got walls here. You've got to be careful. Don't kill yourself.'"
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.