A cross-country road trip ended on yet another sour note Thursday, as the Mariners took their second walk-off loss in three games against the Nationals.

Pinch-hitter Laynce Nix did the damage this time, delivering a bases-loaded sacrifice fly against reliever Chris Ray in front of 21,161 at Nationals Park to complete the sweep with a 1-0 victory.

Former Mariner Michael Morse led off the ninth with a single. Danny Espinosa reached base on a bunt single and Ivan Rodriguez loaded the bases when he attempted a sacrifice bunt. Adam Kennedy threw to third, but he could not beat pinch-runner Brian Bixler to the bag.

With the infield in, shortstop Jack Wilson made a diving stop to rob Jerry Hairston Jr. and force the out at home, but Nix followed with a fly ball to left field and Mike Carp's throw home was up the line and not in time.

Seattle again wasted a dominant effort from its pitcher, and Michael Pineda was perhaps the best of the series' trio that included Erik Bedard and Doug Fister. The three combined to throw 21 innings, struck out 22 and allowed one earned run. None won a game.

The Mariners threatened twice over Jason Marquis' eight innings, but could not capitalize. They had runners on the corners with two outs in the sixth and seventh innings, but Adam Kennedy grounded out to end the sixth and Jack Wilson flied out one frame later.

Marquis took a no-hitter into the sixth -- Pineda's first career hit broke it up -- but he eventually allowed two more, and Seattle's starter was equally impressive over seven innings of scoreless four-hit ball. He struck out nine.

Washington forced Pineda to face more than the minimum only twice -- the fourth inning and the seventh, after which the pitcher's spot led off for Seattle and Pineda exited.

Espinosa attempted to start a seventh-inning rally when he reached on an error by Justin Smoak, who could not catch Dustin Ackley's glove flip to first. A single put two men on before Pineda got his ninth and final strikeout against Marquis to end the inning.

Roger Bernadina led off the fourth with a double, and Pineda walked the next batter. He got an out before Morse singled to load the bases for Espinosa, who hits .340 with 34 RBIs with runners in scoring position.

But Espinosa fouled off Pineda's first offering, then swung and missed the next two. Pineda struck out Rodriguez to leave the Nationals stranded, as neither offense put a blemish on the starters' lines.