(Reuters) - The Washington Nationals cruised to a 7-4 win over the Miami Marlins to extend their lead at the top of the National League East division in the first leg of a doubleheader on Friday.

First baseman Adam LaRoche drove in three runs to increase his team-leading total to 67 on the season while John Lannan improved to 2-0 after striking out four batters and limiting Miami to four hits in six innings.

With the win, the Nationals improved their division lead over the Atlanta Braves to three games.

Marlins four-time All-Star shortstop Jose Reyes singled in the first inning to extend his hitting streak to 21 games while team mate Donnie Murphy left the game in the seventh inning with a strained hamstring.

(Reporting by Frank Pingue in Toronto; Editing by John O'Brien)