The Cubs rallied twice in the late innings, including a game-tying, two-run homer with two outs in the ninth by All-Star Aramis Ramirez, but Brian Schneider hit a game-winning home run in the 12th to lift the Washington Nationals to a 5-4 victory.
"If I'm a fan, I'd be proud of my team," Ramirez said. "Even though we lost, it was a great game to watch."
With the game tied at 4 and two outs in the 12th against Sergio Mitre (2-4), Schneider hit a 1-0 pitch into the right-field bleachers to give the Nationals their sixth straight win and a sweep of the Cubs. At 50-31, Washington has the second-best record in the NL, behind St. Louis (51-30).
"We did a great job coming back," Cubs second baseman Todd Walker said. "But they did all the things right this series. You've got to give them a little bit of credit, too."
The Cubs overcame a 2-0 deficit in the ninth against Chad Cordero as Jeromy Burnitz singled with two outs and Ramirez then crushed a 2-1 pitch into the left-field bleachers to tie the game. Ramirez's 18th homer of the season ended Cordero's streak at 26 straight saves, a franchise record. The D.C. closer had not blown a save since April 21.
With the game tied, 2-2, in the Nationals 11th, Carlos Baerga singled to lead off against Glendon Rusch and reached third on Walker's throwing error. Walker fielded Schneider's grounder and overthrew shortstop Neifi Perez covering second on the potential double play. It was Walker's first miscue this season.
One out later, pinch-hitter Wil Cordero was intentionally walked to load the bases. Brad Wilkerson then lofted a double to center, driving in two.
The Cubs didn't quit, and Jerry Hairston led off the 11th with his third home run. Todd Hollandsworth then tied the game with a two-out RBI double off lefty Joey Eischen (2-0).
"It hurts a lot," Cubs first baseman Derrek Lee said of the loss. "It was a battle, back and forth. We did a great job coming back. We really thought we were going to win that one. They didn't stop. It was a tough loss. It'll make a tough flight."
The Cubs can toast Ramirez and Lee, each named to the National League All-Star team. Lee was the NL's top vote-getter in the balloting. Both will be making their first trips to the Midsummer Classic on July 12 in Detroit.
Back to Sunday's game. Cubs starter Carlos Zambrano struck out seven and gave up two runs on six hits and three walks over seven innings. He was mad at himself after giving up an RBI double to Vinny Castilla in the first.
"I know he's a fastball hitter. That pitch was a stupid pitch," Zambrano said. "That cost me the game. I have four years in the big leagues. I can't make that mistake. I have to be smart."
It doesn't get any easier for the Cubs, who finish the first half against Atlanta and Florida. Both those teams are chasing the Nationals in the NL East.
"That's a great team out there," Ramirez said of Washington. "That's why they're a first-place ballclub."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.