Burnett, Latos among September call-ups (den Dekker DFA)

NEW YORK - The Nationals will have their first set of September reinforcements at their disposal for tonight's series opener against the Mets, including a pair of well-known veterans getting a shot at redemption.

The club promoted seven players to the big league roster this afternoon: left-handers Sean Burnett and Matt Grace; right-handers Mat Latos, Trevor Gott and Rafael Martin; catcher Pedro Severino; and outfielder Brian Goodwin.

Needing to clear two spots on the 40-man roster so Burnett and Latos' contracts could be purchased, the Nationals designated outfielder Matt den Dekker for assignment and transferred right-hander Joe Ross to the 60-day disabled list. (Ross, who has been out since July 3 with shoulder inflammation, is in the final stages of rehab and still will be eligible to rejoin the big league roster in the next week because the 60-day DL move is retroactive.)

All of the promoted players would be eligible for a potential postseason roster because all were in the organization by Aug. 31.

These early September call-ups - there will be more to come in the next few days - include a couple of veteran pitchers who only recently joined the Nationals organization after signing minor league contracts in Burnett and Latos.

Latos, 28, was released by the White Sox on June 17 after posting a 4.62 ERA in 11 starts, but joined the Nats shortly after that. He made six minor league starts between Triple-A Syracuse and the rookie Gulf Coast League, allowing only four earned runs and 20 hits in 28 innings.

With the Nationals still waiting for Stephen Strasburg and Ross to return from injuries, Latos (who had success pitching for manager Dusty Baker in Cincinnati in 2012-13) could be needed to make a start or two.

Burnett, meanwhile, returns to the Nationals four years after helping lead the club to its first-ever division title. The 33-year-old lefty was a stalwart in the Washington bullpen from 2009-12, with a 2.81 ERA in 245 games, but he has pitched in only 16 major league games since due to several arm injuries (including an elbow tear that required his second Tommy John surgery).

The Nationals brought Burnett to spring training as a non-roster invitee, and he made a strong push to make the team with 8 2/3 scoreless innings. He wound up as one of the final cuts, though, then spent the season pitching for four different organization's Triple-A affiliates, finishing with a 2.28 ERA in 47 games.

Also included in today's promotions are young players who either have already spent some time in Washington this season or were on the cusp of joining the roster.

Severino went 7-for-17 with a double and a homer in eight games while Jose Lobaton was on the disabled list earlier this summer. The 23-year-old will give Baker three catchers at his disposal for the stretch run, offering the opportunity to pinch-run for Lobaton or Wilson Ramos late in games.

Goodwin made his major league debut this summer, going 4-for-16 with two RBIs in seven games. A first-round pick in the 2011 draft, the 25-year-old enjoyed a breakthrough season at Syracuse, hitting .290 with a .349 on-base percentage and 14 homers.

Gott was among the last players cut out of spring training but then missed a chunk of time early this season with an elbow injury. The right-hander, acquired from the Angels for Yunel Escobar, wound up with a 4.35 ERA in 33 games at Syracuse.

Grace appeared in 26 games for the Nationals last season, with a 4.24 ERA. The left-hander also missed time with a shoulder injury this season, posting a 2.85 ERA in 35 games at Triple-A.

Martin has pitched in 14 games for the Nationals over the last two seasons. The 32-year-old right-hander had a 4.56 ERA at Syracuse this year.

The move to designate den Dekker for assignment came as something of a surprise, but the 29-year-old has struggled this season, hitting just .208 with a .290 on-base percentage at Triple-A. The emergence of Trea Turner in center field and Goodwin in the minors made him more expendable.

The Nationals are expected to promote more players over the next few days, once their affiliates' seasons end. Both Syracuse and Double-A Harrisburg play their finales on Monday.