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06/13/12 12:44 PM ET

Marrero moving forward in rehab assignment

TORONTO -- Chris Marrero, who has yet to play a game this season after tearing his left hamstring in November, is making good progress on his rehab assignment.

The 23-year-old, who is currently at Double-A Harrisburg, hit .412, with one homer and four RBIs in six games with low Class A Hagerstown and Class A Advanced Potomac.

"Chris is doing better," Nationals manager Davey Johnson said. "He played nine innings the other day. He comes out of it and is still sore. I think he's not risking any injury right now, so he should come through pretty quickly."

In 31 games last season, Washington's 2006 first-round Draft pick batted .248, with 10 RBIs over 109 at-bats.

LaRoche takes day off to rest sore right foot

TORONTO -- Adam LaRoche sat out Wednesday's series finale against the Blue Jays because of a sore right foot.

The Nationals first baseman fouled a ball off his foot in Tuesday night's contest and was still feeling some discomfort.

Nationals manager Davey Johnson said LaRoche received treatment on his foot Wednesday morning -- specifically the arch -- and told Johnson he could probably play, but the skipper elected to give his slugger a day off. Washington has an off-day Thursday, so this will allow LaRoche to get some extra rest.

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"I think he'll be fine, [but] he hit it pretty good," Johnson said. "This field is pretty hard, so might as well give him today."

Toronto's home park, Rogers Centre, has an artificial-turf surface, which is considered much more strenuous on the body, especially the lower half, than natural grass.

LaRoche is having a strong comeback season after being limited to 43 games in 2011 following shoulder surgery, and he is providing the Nationals with production in the middle of the lineup.

The 32-year-old had a team-leading 11 home runs and 42 RBIs -- tied for fourth best in the National League entering play Wednesday -- and was among the top 10 NL leaders in walks, with 29.

Rookie Tyler Moore got the start at first in LaRoche's absence and batted seventh. The 25-year-old Moore was hitting .222 over 27 at-bats this season.

Johnson keeping faith in slumping Zimmerman

TORONTO -- Ryan Zimmerman has been mired in a season-long slump, but Nationals manager Davey Johnson has no intention of moving Zimmerman out of the three-hole in the lineup, where he has hit exclusively this year.

Zimmerman landed on the disabled list toward the beginning of the season with an inflamed joint in his right shoulder, forcing him to miss 13 games in late April and into early May, and has struggled to find his stroke since returning.

"I don't know if it's his approach or what he's thinking, but I know he can be streaky at times," Johnson said. "I sure need him to be comfortable, because he's invaluable to this ballclub. He can help out a whole lot.

"He's hard for me to read a little bit. He's really not attacking the ball. ... I don't know if his shoulder is bothering him or not, but we certainly need him."

Entering play Wednesday, the All-Star third baseman was batting .239, with three home runs, 22 RBIs and a .655 OPS over 46 games.

Zimmerman is coming off an injury-plagued 2011 that saw him post career lows in a number of offensive categories, but Johnson is fully confident the 27-year-old's production will get back to his pre-2011 numbers, when he posted consecutive seasons in which he hit at least 25 home runs and logged an OPS above .885 from 2009-10.

"He's too good a hitter to keep struggling," Johnson said. "We are at the early stages of the season, so there is plenty of time to pick up the slack."

Chris Toman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.