Aramis Ramirez and Carlos Pena hit back-to-back homers and the Cubs beat the Washington Nationals 4-3 Thursday.
Ramirez's two-run shot in the seventh was his 21st of the season, and gave him 16 homers since June 25, the most in the major leagues since then.
Pena followed Ramirez with a clout that curled around the pole in right field and landed on Sheffield Avenue and put the cubs up 4-1.
Ryan Dempster (10-8) limited Washington to a first-inning home run by Ryan Zimmerman and went seven innings, allowing three hits, walking two and striking out six.
Washington loaded the bases and scored a run in the ninth against Carlos Marmol, but he recovered to get his 26th save.
Wilson Ramos hit a high chopper off Marmol that he beat out for an infield single, scoring Jonny Gomes. But Marmol struck out Brian Bixler and got Rick Ankiel on a fly ball to the wall in center to end the game.
Marmol has converted seven straight saves since returning to closer's role on July 31.
Washington also scored a run in the eighth, when pinch-hitter Bixler hit an infield single. Ankiel followed with a single, but Cubs reliever Kerry Wood struck out Danny Espinosa and Zimmerman.
Wood has struck out the last eight batters he's faced, tying the Cubs' record by a reliever since the mounds were lowered in 1969.
Washington starter Jordan Zimmermann (7-10) allowed four runs and nine hits in 6 2-3 innings. He walked two and struck out seven.
The Cubs have won nine of their last 11 games and got their third straight series win at home, something they hadn't done since 2009.
Zimmermann held the Cubs to one run on six hits through six innings but ran into trouble after striking out the first two batters of the seventh. Johnson laced his third single of the game into left field. Ramirez followed with a shot into the left-field bleachers, putting the Cubs up 3-1 before Pena's homer chased Zimmermann.
Dempster won his third straight start and reached 10 wins for fourth straight season. He's won 10 or more seven times in career. Only Fergie Jenkins (15) and Reggie Cleveland (8) have more 10-win seasons among Canadian-born pitchers.
Alfonso Soriano hit an RBI triple and Reed Johnson added three singles for Chicago. Johnson went 7 for 8 at the plate over the last two games of the series.
Zimmerman opened the scoring in the first when he homered onto Waveland Avenue beyond the left-field bleachers to extend his hitting streak to 19 games, the second-longest active streak in the big leagues behind the 31-game streak of Atlanta's Dan Uggla.
The 91 first-inning runs the Cubs have allowed are most in baseball.
Chicago tied it in the fourth on Soriano's RBI triple. Right fielder Jayson Werth dove for the ball but it clipped the end of this glove and rolled to the wall. Byrd scored and Soriano wound up at third with his first triple since Aug. 23 of last season.
Zimmermann reached 145 innings for the season, leaving him two or three starts left before he reaches his limit of 160 for the season. He had Tommy John surgery nearly two years ago.
NOTES: Cubs starter Andrew Cashner completed a bullpen session before Thursday's game with no problems, the latest step in his recovery from a strained right rotator cuff. Asked if he expected to be back before the end of the season, Cashner said, "There is no doubt in my mind." . The Cubs travel to Atlanta for a three-game weekend series against the Braves, the first leg of a six-game road trip that will also stop in Houston. Carlos Zambrano is set to face Atlanta's Mike Minor on Friday. Zambrano has hit 23 career HRs. He tied Walter Johnson for ninth among pitchers with his homer off Johnny Cueto on Aug. 6. Zambrano is 0-4 with a 6.24 ERA in last 10 starts against Atlanta since July 13, 2003. . The Nationals' Livan Hernandez will start the opener for Washington against Philadelphia's Cole Hamels. Hernandez hasn't won at Citizens Bank Park since May 31, 2006. . Washington's Michael Morse had to leave the game after being hit on the elbow by a pitch. . Despite an announced crowd of 34,733, just about half the seats were actually occupied on a picturesque afternoon at Wrigley Field. Thursday's game was a makeup of Monday's rainout. It was the Cubs' lowest announced crowd since their June 1 game against Houston.