Watch: Nationals' Ildemaro Vargas Hits Game-Winning Homer Off Paul Sewald

Sewald hadn't given up a run since July 26. Over the last ten innings he had pitched, he had walked just one batter, allowing no hits and no runs, and striking out nine.

Mariners' manager Scott Servais hasn't named a closer and has been running his bullpen via 'closer by committee.'

Nationals' reliever Carl Edwards Jr. blew his second save of the season in the bottom of the 8th, giving up a home run to budding Mariners' star outfielder Julio Rodriguez.

With two outs in the top of the 9th, Vargas sent a two-run homer just over the right-field wall, giving the Nationals the 3-1 lead.

Vargas has bounced around a number of teams over the past three years, making stops in Arizona, Minnesota, Chicago, Pittsburgh and most recently, Washington. He opened the season with the Cubs, but was designated for assignment May 15 upon the return of outfielder Ian Happ from the Injured List.

Vargas is slashing just .130/.231/.579 in Chicago in 2021.

Since joining the Nationals, he's seemingly turned a corner. Through 18 games, the 31-year-old infielder is hitting .301/.344/.737 with two home runs and four RBI.

With the victory, the Nationals improve to 42-83 on the season, the worst record in Major League Baseball.

The Mariners fall to 67-57, two games up on the Baltimore Orioles, who play the Chicago White Sox Wednesday night.