Ryan Mattheus (foot) will continue his minor league rehab assignment with Double-A Harrisburg.

Mattheus allowed a pair of solo homers Sunday in his first rehab appearance with High-A Potomac. The 28-year-old right-hander has been on the disabled list since May 21 with plantar fasciitis in his left foot.

Ryan Mattheus (foot) is scheduled to begin a minor league rehab assignment on Sunday.

Mattheus made it through a bullpen session Wednesday without incident and is scheduled to throw a simulated game on Friday. The righty has been on the disabled list since May 21 with plantar fasciitis in his left foot.

Ryan Mattheus (plantar fasciitis) threw a pain-free bullpen session Wednesday.

Nationals manager Davey Johnson did note that Mattheus still has some "puffiness" in his left foot, but this should still be viewed as a big step in the right direction. Mattheus will have pitchers' fielding practice on Thursday. It's not clear when he'll begin a rehab assignment.

Ryan Mattheus (plantar fasciitis) is still dealing with tenderness in his left foot.

Mattheus is reportedly progressing well, but the Nationals are worried he could re-injure himself by ''moving off mound'' and want to bring him along slowly. He's no longer in a walking boot and recently began throwing from a distance of 120 feet. The 28-year-old right-hander has a 2.25 ERA and 13/7 K/BB ratio in 20 innings of work this season and will return to the Nationals bullpen when healthy.

Ryan Mattheus (plantar fasciitis) is out of a walking boot and throwing from a distance of 120 feet.

Mattheus was placed on the disabled list last week after being diagnosed with a partial tear in the plantar fascia in his left foot. He's ahead of schedule right now, but the Nationals' trainers will bring him along slowly to avoid a setback.

The Nationals are expected to place Ryan Mattheus (plantar fasciitis) on the disabled list Tuesday.

Mattheus is currently dealing with plantar fasciitis in his left foot and is scheduled to see a specialist Tuesday in Baltimore. While it's not a major injury, it's not clear when he'll he ready to pitch again. Chien-Ming Wang (hamstring) is expected to be activated from the disabled list to replace him on the active roster.

Ryan Mattheus is scheduled to get X-rays on his left foot Monday in Philadelphia.

Mattheus has felt something for the past few weeks and may have aggravated it in Monday. The Nats are hoping it's plantar fasciitis, but we should know more after he sees a specialist in Baltimore on Tuesday. Chien-Ming Wang could replace him on the active roster if he requires a stint on the disabled list.

Nationals activated RHP Ryan Mattheus from the 15-day disabled list.

Mattheus missed a little over three weeks due to tightness in his right shoulder. The 27-year-old has registered a 2.40 ERA and 1.27 WHIP through 30 innings this season.

Ryan Mattheus (shoulder) threw a successful simulated game Saturday and is slated to be activated from the disabled list early this week.

"He threw the ball fine," said Nationals manager Davey Johnson. "His velocity still is not quite where it was before he got hurt." Mattheus hasn't pitched since August 25 due to right shoulder tightness.

Ryan Mattheus (shoulder) threw another successful bullpen session Wednesday.

He threw another 25 pitches -- the same number he threw Sunday. "[The bullpen session] was great. Better than the first one," Mattheus said. "The ball is coming out real good. I had no issue with the arm, which is the biggest thing. ... I let it go a little bit more and it felt game like. My stuff was really good." Mattheus is scheduled for a simulated game this weekend before being activated early next week.

Ryan Mattheus (shoulder) had a successful 25-pitch bullpen session Sunday.

The Nats are hoping he'll be ready to rejoin the bullpen by September 20. "There is not going to be anything holding me back from getting back out there," Mattheus said. "I don't know how many innings it will be, but I think I'll be out there pretty soon."

Ryan Mattheus (shoulder) is scheduled to throw a bullpen session on Sunday.

Mattheus hasn't pitched since August 25 due to right shoulder tightness. The Nationals are still hopeful that he will be able to make an appearance or two before the end of the season. The 27-year-old right-hander had a 2.40 ERA and 11/14 K/BB ratio over 30 innings prior to the injury.

Nationals placed RHP Ryan Mattheus on the 15-day disabled list with right shoulder tightness.

Mattheus has been battling the discomfort for over two weeks and will now rest up until mid-September. The righty has a 2.40 ERA and 1.27 WHIP so far this season.

Ryan Mattheus was pulled from Thursday's game due to tightness in his right shoulder.

Mattheus is considered day-to-day for now, but will probably undergo a range of precautionary tests. The right-hander has a 2.40 ERA and 1.27 WHIP on the year.

Ryan Mattheus returned to action on Saturday August 20.

Ryan Mattheus was pulled from Thursday's game after feeling tightness in his right shoulder.

Mattheus did not throw a pitch in the game, as he felt the discomfort on one of his warmup tosses. The 27-year-old right-handed reliever is considered day-to-day.

Nationals re-signed RHP Ryan Mattheus to a one-year contract.

Mattheus missed nearly all of last season while recovering from Tommy John surgery but pitched well late in the year. He'll have a shot to win a spot in the major league bullpen.

Nationals sent RHP Ryan Mattheus outright to Triple-A Syracuse.

The Nats acquired Mattheus from the Rockies in the Joe Beimel deal at the 2009 trade deadline. He missed nearly all of last season while recovering from Tommy John surgery, but he's shown some upside since being converted from starter to reliever. He will be in the Nats' camp as a non-roster invitee.