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8/29/2014 10:47 P.M. ET

Zimmerman's strained hamstring continues to improve

SEATTLE -- Nationals third baseman Ryan Zimmerman had an MRI on Monday and the results yielded good news, according to manager Matt Williams. Zimmerman's right hamstring is healing nicely. He has already started jogging and has been throwing every other day.

Zimmerman's first test will be running at full speed, then running around the bases and finally taking batting practice, according to Williams.

"He is making the progress that he should make," Williams said. "The strength will increase now that he could start pushing it. ... Once he feels good about that, he can get out and start running and doing some sprint work, all the while being mindful that you don't want to push it too hard. If you lose him, you lose him for good at this point."

Williams said recently that he hopes to get Zimmerman back on the field by late September. However, no timetable has been set -- yet. Zimmerman sustained a Grade 3 hamstring strain, which takes a while to heal.

Jewett managing against Nats in Seattle

SEATTLE -- Mariners bench coach Trent Jewett will manage the Mariners on Friday and Saturday while manager Lloyd McClendon attends his daughter's wedding.

From 2011-13, Jewett was one of Washington's Major League coaches, first as a first-base coach in 2011-12 and then spent all of last season as the third-base coach. After the 2014 season, Jewett interviewed for the Nationals' managerial job after Davey Johnson retired, but the job went to Matt Williams.

Jewett then decided to leave Washington and join the Mariners' staff. He has a long working relationship with McClendon which dates back to their Pittsburgh days in 1996. He said he would have stayed with the Nationals if not for his relationship with McClendon.

"It's a long-standing relationship. ... I admire a lot of his traits. We can -- most of the time -- get along really well, but we argue well, too," Jewett said. "There is not a whole lot of things in baseball that would take me out of that situation [in Washington] if it were up to me. Lloyd McClendon is one of them, the way this organization [the Mariners] treated me when I came here to speak with them."

Jewett said he misses a lot of the relationships he had in the Nationals' organization. He was seen talking to shortstop Ian Desmond before Jewett had his meeting with the Seattle media on Friday.

"That's a great clubhouse [in Washington]. I know that. It's run by tremendous people. There are a lot of things that I miss. I see a lot of the same traits [in Seattle]," Jewett said.

He is not surprised to see the Nationals in first place. He said they have a firm foundation. He said he would be surprised if they are not a good ballclub for many years to come.

Nats ink two-year extention with Class A Hagerstown

SEATTLE -- The Nationals announced the signing of a two-year player development contract extension with the Hagerstown Suns of the Class A South Atlantic League through the 2016 season.

The Nationals began their relationship with Hagerstown in 2007 after ending a six-year run with the Savannah Sand Gnats. The Suns are 530-501 (.514) since aligning with the Nationals, including three consecutive 80-plus win seasons and three straight playoff berths (2012-14).

In that span, Suns fans have enjoyed exposure to the big league talents of Bryce Harper, Steven Souza Jr., Stephen Strasburg and Jordan Zimmermann.

The current version of the Hagerstown Suns started in 1992 as an affiliate of the Toronto Blue Jays and has been a member of the South Atlantic League for all of its 22 seasons. The Suns reside in the South Atlantic League's seven-team Northern Division with Delmarva, Greensboro, Hickory, Kannapolis, Lakewood and West Virginia.

The Nationals' Class A affiliate is just 70 miles north of Washington, D.C., allowing for convenient travel between the Major League club and the affiliate.

"We are happy to extend our player development contract with the Hagerstown Suns, continuing our seven-plus year relationship with them," general manager Mike Rizzo said. "Some of the organization's brightest talents have spent significant time learning the game with Hagerstown, before advancing further through our system. We're glad to continue our working relationship."

Worth noting

• Jayson Werth was the designated hitter against the Mariners on Friday. It gave him a chance to rest his shoulder and ankle and give Nate Schierholtz a chance to start in right field. Williams wouldn't guarantee that Werth would be the DH throughout the series in Seattle.

• The Nationals are expected to make their callups by Monday when the team plays the Dodgers. Blake Treinen, Aaron Barrett and Michael Taylor are expected to join the team that day.

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.