Alfonso Soriano's two-run homer keyed a seven-run fourth inning and the Chicago Cubs completed a four-game sweep of the Washington Nationals with an 11-3 victory Sunday.

Soriano's 16th home run, his second in two games after a drought of 120 at-bats, began the biggest inning of the season for the Cubs. Starting pitcher Kevin Hart also contributed by faking a bunt and punching an RBI single.

Adam Dunn hit his 24th homer but Washington dropped to 0-4 under new manager Jim Riggleman, who took over when Manny Acta was fired at the All-Star break.

Jake Fox had three hits and a career-high four RBIs. His three-run homer in the sixth gave Chicago an 11-2 lead.

Mike Fontenot and Micah Hoffpauir also had three hits for the Cubs, who outscored Washington 26-11 in the sweep. Chicago has won six of seven.

The Cubs had 16 hits, equaling their season high.

Hart (1-1), who spent the All-Star break pitching at Class-A Peoria, was recalled to make the start. He pitched five innings, allowing two runs and five hits while walking five and striking out one. The hit and RBI were the first of Hart's career.

Chicago's seven-run fourth also included two Nationals errors and RBI singles by Kosuke Fukudome, Derrek Lee and Jake Fox and a sacrifice fly by Ryan Theriot.

Garrett Mock (0-3), who was summoned from Triple-A Syracuse after winning five straight there, allowed seven runs _ four earned _ in 3 1-3 innings for Washington.

The Nationals scored in the second and third on sacrifice flies by Alberto Gonzalez and Ryan Zimmerman. Dunn connected in the seventh.

NOTES: To make room for Hart, the Cubs sent OF Sam Fuld to Triple-A Iowa. ... J.D. Martin will make his major league debut Monday as the Nationals' starter against the New York Mets. Martin is 8-3 with a 2.66 ERA at Syracuse. Washington will put LHP Scott Olsen on the 15-day disabled list with a back injury. ... SS Cristian Guzman, who missed the previous two games with bunions, pinch hit in the fourth inning. ... The Nationals have left the bases loaded four times in the past three games. ... Dunn's 24 homers are the most by a Nationals left-handed hitter in a season.