Philadelphia Phillies relief pitcher Jonathan Papelbon
Phillies relief pitcher Jonathan Papelbon reacts after a strikeout to end the game against the Baltimore Orioles at Citizens Bank Park in Philadelphia, June, 18, 2014. The Phillies won 2-1. Reuters/Bill Streicher-USA TODAY Sports

Days before the trade deadline, the Washington Nationals have acquired veteran pitcher Jonathan Papelbon in a trade with the Philadelphia Phillies.

Papelbon will reportedly play the closer role in Washington, an assurance the pitcher demanded before allowing the trade, as per reports. The team confirmed the deal on Twitter.

"Papelbon is our ninth-inning pitcher," Nationals general manager Mike Rizzo said to confirming that the reports about the demand for the closer role. "Drew [Storen] will pitch the ninth inning at times when Papelbon is unavailable and be our setup guy in the eighth inning as we are constructed today. Paps hasn't pitched too many three-days-in-a-row stints. We're going to be careful with him, and we feel that we've got two terrific, elite ninth-inning guys who can close out games in pressure situations."

The 34-year-old Papelbon also inked a deal to stay in Washington until the 2016 season. Meanwhile the Phillies, who have the worst record in the league with 38 wins against 63 losses so far this season, will be acquiring right-hander prospect Nick Pivetta, who played in the Double-A league.

The Nationals are the current leaders in the East Division of the American League with a 52-46 win-loss record. With a lost season, the Phillies are expectedly becoming the sellers days before the MLB trade deadline on July 31. Philadelphia is also aggressively looking for trade partners for another pitcher in Cole Hamels, who is reportedly being targeted by the Texas Rangers, Los Angeles Dodgers, Houston Astros and San Francisco Giants, among other MLB teams.