Updated at 6:30 p.m.
Right-hander Joe Ross, one of the players acquired in last winter's complex trade that most notably will bring shortstop Trea Turner to the Nationals next week, will be promoted from Class AA Harrisburg and start Saturday's game against the Cubs, manager Matt Williams announced.
Ross, 22, isn't currently on the Nationals' 40-man roster, but he can have his contract purchased, with the organization clearing a spot for him by transferring one of several injured players (Craig Stammen, Jayson Werth, Reed Johnson, Nate McLouth) from the 15-day to the 60-day disabled list. Another player will have to come off the 25-man active roster in exchange for Ross.
Though the Nationals have starting candidates with experience at both Class AAA Syracuse and the big leagues — right-handers A.J. Cole and Taylor Hill both are currently on the major-league roster — they will instead turn to the promising (if inexperienced) Ross to make his debut Saturday.
"We're excited to see him, having come from a different organization," Williams said. "He's pitched very well, though. He's commanded the zone and done everything that's asked of him. So he's going to get a chance."
Ross is 2-2 with a 2.81 ERA in nine starts at Harrisburg, striking out 54 batters while walking 12 in 51 1/3 innings. He was already on schedule to start Saturday against Trenton.
A first-round pick of the Padres in 2011, Ross was part of December's complex, 3-team trade that saw the Nationals send outfielder Steven Souza Jr. to the Rays while also acquiring a player to be named later from San Diego. That player, prized shortstop prospect Turner, will finally be eligible to be dealt June 13.
The 6-foot-4 Ross is the younger brother of Padres right-hander Tyson Ross, who beat the Nationals at Petco Park last month.
"I think he was a guy that we thought that would be quick through the minor leagues for us," general manager Mike Rizzo said. "But this has accelerated his development even a little faster than I thought he would."