Giolito and Lopez continue throwing in Florida, will head north in late April (with P-Nats roster)

The Nationals released rosters for their minor league affiliates Tuesday. Noticeably absent from the high Single-A Potomac Nationals are top pitching prospects Lucas Giolito and Reynaldo Lopez.

The pair has remained in Viera, Fla., at the Nationals training facility and are in good health, just a couple of weeks behind their teammates. They have been working on a throwing program since their arrival in Florida in February, according to Nationals assistant general manager and vice president baseball operations Doug Harris.

"We wanted to monitor every step of the way from a physical perspective," Harris said. "There are no (physical) issues whatsoever. They are in their mound progression. They will be a couple of weeks behind, but they both look very good."

Harris said Giolito and Lopez reached their innings limits last season at low Single-A Hagerstown. Giolito threw 98 innings last season, while Lopez tossed 83 1/3 innings between Hagerstown and short-season Single-A Auburn.

"They both maximized their innings last year," Harris said. "We anticipate coming close to that, probably coming close to that again this year. It will give us an opportunity to monitor every step of the program and in the end, it's going to be a nominal innings difference. But it gives us the ability to control every step of it early on."

Harris expects the pair to be ready to pitch in minor league games by the end of this month. It has not been confirmed, but most likely they will report to Potomac.

"I would anticipate the end of April is probably a pretty good target," Harris said. "They're both in their mound progression. They are throwing live BPs. They will be competitive this week. They are not significantly behind anybody by any stretch of the imagination."

The Potomac roster includes shortstop Wilmer Difo, outfielder Rafael Bautista, and pitchers Dakota Bacus and Jake Johansen.

2015 Potomac Nationals opening day roster:

PITCHERS (13)
RHP Dakota Bacus
RHP Cody Davis
RHP Brian Dupra
RHP Jake Johansen
LHP Nick Lee
LHP David Napoli
RHP Nick Pivetta
RHP Brian Rauh
RHP Manny Rodriguez
RHP Blake Schwartz
LHP Matthew Spann
RHP Wander Suero
LHP Justin Thomas

CATCHERS (2)
C Spencer Kieboom
C Craig Manuel

INFIELDERS (6)
IF Christopher Bostick
IF Wilmer Difo
IF Khayyan Norfork
3B Drew Ward
IF/OF John Wooten
1B James Yezzo

OUTFIELDERS (4)
OF Isaac Ballou
OF Rafael Bautista
OF Estarlin Martinez
OF Brandon Miller