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WASHINGTON -- This is the sort of return the Washington Nationals are expecting for their huge investment in Jayson Werth: The moxie to pull off a steal of third in the 10th inning at a time when his every mistake has been generating a round of boos.

Moments after he stunned the ballpark by swiping the bag, Werth was crossing home plate with arms raised, his teammates headed his way to celebrate. Werth had scored on a wild pitch, and the fans that had been so hard on him the last few days were cheering his daring in a 5-4, Fourth of July matinee win over the Chicago Cubs.

"Cheer me, boo me, whatever," Werth said. "I'm still going to go out there and play my game."

Werth's game was all over the place Monday. He was caught stealing second in the fourth. He struck out with two outs and the bases loaded when the score was tied in the seventh, the large holiday crowd deriding him during his walk back to the dugout. He had his first two-RBI game since May 31, but he knocked in one of those runs with a broken-bat single and the other with a groundout to first.

Yet he also threw a runner out at home from right field to stifle a Cubs rally in the sixth. And then there was that eventful 10th.

After drawing a leadoff walk off Marcos Mateo (1-2), Werth advanced on a sacrifice by pinch-hitting pitcher Livan Hernandez. Mateo left the game with an elbow injury and was replaced by Carlos Marmol. On Marmol's first pitch to Ivan Rodriguez, Werth strolled to a big lead and took off.

"There was no sign for that," Washington manager Davey Johnson said. "It was just his read -- and boom -- he's over there. That's a winning attitude."

Said Werth: "I just felt like it was time to make something happen. ... It's a funny game. You steal third and score the winning run. If he inside-moved me (for a pickoff attempt) right there, I'm probably the goat."

Marmol was given extra time to warm up when he unexpectedly got the call to come on for Mateo, who will return to Chicago to have an MRI, but the unusual circumstance made the Cubs closer ripe for the surprise from Werth.

"You have to change your routine. I never do that before, it's tough," Marmol said. "I was paying attention to the hitter. My mistake, I paid for it."

Marmol went on to uncork a 2-2 pitch that sailed way outside to Rodriguez. Werth scored. Game over. Another thriller. The Nationals' last eight wins have been either by one run or in extra innings, and four of their last eight home games have been walkoff victories. They are outscoring teams 58-26 for the season in the ninth inning and later.

Henry Rodriguez (3-1), pitched the 10th to get the win for the Nationals, who improved to 3-5 under Johnson and are back again at .500.

But the other big numbers everyone have been noticing belong to Werth, who is in the first year of a seven-year, $126 million contract. He's batting .224, including .167 since June 1. He has 10 home runs and 30 RBIs.

"I'd like to get going a little bit offensively, but as long as we're winning and I'm helping the team win, doing the little things, I'm satisfied with it," Werth said. "I feel like the offense is going to come. I've still got the second half of the season here. A lot can happen. You get hot; you get cold. You keep hustling. You keep playing the game hard, you keep playing it the right way."

Werth played despite getting hit by a pitch on his left wrist Sunday. Johnson said he would have liked to rest the outfielder, but the Nationals also started without third baseman Ryan Zimmerman (sore abdomen) and first baseman Michael Morse (bruised forearm). The thin bench meant the manager had to use two off-day starting pitchers (Jason Marquis and Hernandez) as pinch hitters.

The Cubs opened a seven-game road trip by ending a seven-game Nationals Park winning streak. Casey Coleman, who had a 7.78 ERA in his two previous stints with the Cubs this season, was recalled from the minors for the game after scheduled starter Ryan Dempster was hospitalized over the weekend with stomach and back pain.

Coleman allowed three runs over 5 1/3 innings, one of them unearned following a booted groundball by first baseman Carlos Pena in the first inning.

"Little things haven't really gone the way we wanted them too," Cubs outfield Marlon Byrd said. "It's been one of those years. Everything's weird."

Game notes

Quade said Dempster is day to day but is expected to make another start before the All-Star break. ... To make room for Coleman, reliever Chris Carpenter was optioned to Triple-A Iowa. ... Zimmerman was feeling sore in the abdominal area where he had surgery earlier this year. He was removed for a pinch runner immediately after he walked as a pinch hitter in the seventh. "Anything like that, I'm not taking a chance where he might reinjure that thing," Johnson said. ... Morse has a bruised forearm after getting hit by a pitch Saturday night. ... Nix played his first major league game at first base, moving from left field during a double switch in the seventh. ... Cubs reliever Kerry Wood mixed wildness with effectiveness. He walked in the run that tied the game in the seventh before striking out Werth. His final line: One inning, three walks, three strikeouts, one wild pitch, one hit batter.