Third base umpire Greg Gibson watches as Washington third baseman Ryan Zimmerman tags out Florida’s Omar Infante on a fifth-inning double steal. The Marlins fell behind by four runs before rallying for a 7-4 victory. (J Pat Carter/Associated Press)

During the opening stages of Wednesday night’s game, the Washington Nationals played compelling, winning baseball. They unnerved the other team’s starter, played crisp defense and seized a lead that should have been comfortable. And then, as is their custom against the Florida Marlins, they quickly managed to make all that irrelevant.

The Marlins spotted the Nationals four runs and then beat them 7-4, the Nationals’ 41st loss to the Marlins in 54 games since 2008. The Nationals (1-4) lost their seventh straight against Florida and their second straight this year, ensuring their search for their first series win of 2011 will restart Friday in New York. Well, hey, Bryce Harper debuts Thursday night in Georgia.

The results remain the same against the Marlins, but the culprits changed. Wednesday, before 13,825 at Sun Life Stadium, Livan Hernandez walked five batters in four innings — one more than Nationals starters had allowed combined in their first four games — and yielded four runs in a fifth inning that erased the Nationals’ lead. Chad Gaudin relieved him in the sixth and promptly yielded two runs, the go-ahead run scoring on Omar Infante’s RBI single.

The Nationals’ offense mostly reentered hiding once the lead was lost. Between the fifth and eighth innings, only Rick Ankiel reached base, a bloop single to right that was eliminated by a double-play ball from the next hitter, Danny Espinosa. The Nationals managed a brief rally in the ninth when Ian Desmond singled against Marlins closer Leo Nunez, his fourth hit of the night, and Jayson Werth walked, bringing Ryan Zimmerman to the plate as the tying run. But Zimmerman struck out swinging at a high, 95-mph fastball, and Werth and Desmond became two of the 20 base runners the Nationals have stranded over the past two days.

The Nationals built their lead as Desmond, having returned to the leadoff spot after Manager Jim Riggleman considered moving him down, knocked three hits in his first three at-bats, two doubles and an RBI bunt single. Desmond’s second double, a laser to left-center, scored Ivan Rodriguez and put the Nationals up 4-0 in the fourth.

The game unraveled in the fifth, when Hernandez experienced his second spasm of wildness. He loaded the bases in the first with three straight walks before escaping. He walked consecutive batters with two outs in the fifth to again load the bases, bringing up John Buck.

Hernandez worked a full count and threw Buck a 68-mph curveball, an audacious choice, and an 87-mph fastball, and Buck fouled both pitches away. Hernandez tried one more fastball. Buck smashed it to right center. Hernandez turned around, watched the ball fly for a moment and doubled over on the mound.

The ball ricocheted off the top of the fence and back into the field. All three runs scored easily, Buck stood on third with a triple and the Nationals had lost their grip on the game.

After they stranded 12 runners Monday night, the Nationals played the kind of offense that doesn’t require clutch hits. In the second, the Nationals scored three runs, sent eight men to the plate — and hit two balls out of the infield.

Ankiel led off with a walk, and with Espinosa batting, he bolted for second. Espinosa nailed a single that rolled over the precise spot Infante, the Marlins’ second baseman, had deserted in order to cover second base, a clinical hit-and-run that placed runners on first and third.

When Ivan Rodriguez hit a chopper to third, Ankiel sprinted home as Donnie Murphy fired home. Ankiel slid to the right of home plate, swiping his left hand over the tip of the dish, just out of the catcher’s reach, to score the Nationals’ first run.

Hernandez bunted the runners to second and third, and up came Desmond. He dropped a bunt to third base, catching Murphy — and maybe Espinosa, too — by surprise. But Espinosa scored easily and Desmond glided safely to first. After Werth walked, Zimmerman gave the Nationals a 3-0 lead with a sacrifice fly to right.

But, as any of the Nationals’ leads tend to do against the Marlins, it crumbled. The Nationals showed one more sign of fight before it ended. After Riggleman trudged to the mound to pull reliever Todd Coffey, Coffey barked at home plate umpire Tim Tschida. The umpire ejected Coffey, who tossed his glove and stomped to the plate to reinforce his argument.