MIAMI — The Florida Marlins' new leadoff hitter is so fast he can beat out a home run.

Emilio Bonifacio became a crowd favorite in his Marlins' debut Monday, hitting the majors' first inside-the-park homer on opening day since 1968 and going 4-for-5 in a 12-6 victory over his former team, the Washington Nationals.

Florida also hit three homers over the fence, including Hanley Ramirez's grand slam.

The offense was a bonus coming from Bonifacio, who joined Florida with a reputation as a slick-fielding but light-hitting speedster. He was summoned for a curtain call following his first big league homer, which landed short of the warning track but sailed over center fielder Lastings Milledge because he was playing so shallow.

The last inside-the-park home run on opening day was by Boston's Carl Yastrzemski on April 10, 1968.

Bonifacio stole three bases and scored all four times he reached. Jorge Cantu and Jeremy Hermida hit Florida's first two homers. Ramirez drove in five runs and Cantu three. Ricky Nolasco pitched six innings to win in his first opening-day start.

The Nationals looked much like the 2008 team that lost 102 games, most in the majors. Starter John Lannan departed after three innings trailing 6-1, the bullpen fared no better and a defense that was woeful last year committed two errors.

One bright spot for Washington was the bat of newcomer Adam Dunn, who drove in four runs with a homer and a double.

Bonifacio singled, stole a base and scored in the first, then did it again in the third. But his best moment came with a runner on in the fourth, when he drove Jesus Tavarez's 3-2 pitch to deep center. Milledge retreated and dove but failed to come up with the ball, and Bonifacio flew around the bases and slid home ahead of the throw.

The roar from the crowd of 34,323 held up further play until Bonifacio re-emerged from the dugout with a wave.

Bonifacio made two nice defensive plays at third but committed an error when he whiffed trying to catch a liner by Ryan Zimmerman in the sixth. Dunn followed with a three-run homer to cut the margin to 8-5, but Ramirez dashed the Nationals' hopes for a comeback with a grand slam off Steven Shell in the bottom of the inning.

Nolasco struck out six and allowed five runs, four earned.

Hoping to rely less on the home run this season, the Marlins played small ball to score twice in the first. Bonifacio led off with a single, stole second and came home when left fielder Dunn got a poor jump on John Baker's fly, which landed for a double.

Ramirez sacrificed, giving him one more sacrifice than he had last season. The strategy paid off when Baker scored on Cantu's groundout for a 2-0 lead.

Bonifacio started things again in the third with a single. He took second on a groundout and stole third, allowing Ramirez to squib an RBI double over drawn-in first baseman Nick Johnson.

Cantu followed with a two-run homer, and one out later Hermida also homered for a 6-0 lead.

Notes: Bonifacio's inside-the-park homer was the first for Florida since Ramirez hit one against Cincinnati on Sept. 27, 2006. ... The gametime temperature was 90 degrees. ... Johnson went 1-for-4 playing in his first game in nearly 11 months following a wrist injury. ... Left-hander Scott Olsen starts for the Nationals on Tuesday after pitching for Florida in 2005-08. "You have relationships with the guys, but once you're on the field, it's business as usual," Olsen said. "It's going to be a typical game."