Morton has given up two earned runs or less in five of his first seven starts this season for Pittsburgh. He leads the Pirates' starting rotation with a 3.13 ERA.
Zimmermann, his opponent on Tuesday, is coming off a career game, as he struck out 11 Braves in 6 1/3 innings last Thursday.
At 27 and 24, Morton and Zimmermann represent young talent in their teams' respective rotations, but share a common hurdle with getting run support.
The Pirates have scored the sixth-fewest amount of runs in the Majors with 147, while the Nationals are not far behind, with their 157 runs the ninth-lowest output. In eight starts this season, Zimmermann has gotten 28 runs from the Washington offense -- good for only 3.5 runs per outing.
However, against Morton, Zimmermann may get more support than expected.
Despite the right-hander's stellar numbers from this year, Morton did not fare well against the Nationals last season. In his start against Washington, Morton lasted only 3 2/3 innings, having given up two earned runs off eight hits with a strikeout.
Now, Morton looks for revenge and is going for a third straight win for the first time in his career.
Pirates: Diaz looking to continue strong May
Despite going 0-for-2 with a walk Monday night, Pittsburgh outfielder Matt Diaz's bat has come alive in May.
After hitting only .208 with nine strikeouts in April to start the season, Diaz has turned things around. His batting average is up to .280 this month and just two strikeouts.
"Actually he's freed up his hands a little more," Pirates manager Clint Hurdle said of Diaz. "It's May, and he hits a lot better in May than he did [before], and that's got a little history to it."
Hurdle said the coaching staff has done hand-related, mechanical work with Diaz's swing to try to help him.
Nationals: Ankiel returning to health
Washington outfielder Rick Ankiel (sprained right wrist) took batting practice for the first time Monday after being put on the 15-day disabled list on May 3.
Pending another batting-practice session Tuesday, Ankiel will begin a rehab assignment.
"Everything went well, I felt good. I like the way it went," Ankiel said. "I want to come back and help the team and compete. I want to keep that competitive fire out there."
Ankiel injured the wrist attempting to catch a foul ball against the Phillies earlier this season. He is hitting .221 with one home run and seven RBIs in 2011.
The Nationals are one game back of .500, but remain 5.5 games back from the division-leading Phillies, who are tied for the most wins in the Majors. ... Pittsburgh is looking to snap a six-game losing streak, which has put the Pirates that many games back of first in the NL Central.