WASHINGTON -- Though the Phillies hope to get Rhys Hoskins back at some point during their four-game series at Nationals Park, they'll be without Andrew McCutchen a bit longer.

While manager Joe Girardi said there was "nothing alarming" on the MRI results on McCutchen's left knee, the club placed him on the 10-day injured list prior to Monday's series opener due to inflammation. Andrew Knapp was reinstated from the paternity list to take McCutchen's place on the active roster.

"We just didn't feel like it'd be a couple days," Girardi said. "We think it'll calm down with this stint. Our hope is to get him back when it's over."

Hoskins, meanwhile, remains day to day with a left groin issue.

The duo has been the Phillies' top run producers this season. Hoskins leads the team with 63 RBIs, while McCutchen isn't far behind with 58 -- but the latter has arguably been Philadelphia's best hitter for the past two months.

McCutchen is hitting .271 with 13 homers, 37 RBIs and a .964 OPS in 49 games since the start of June. To put those numbers in perspective, that works out to a 42-homer, 122-RBI pace over 162 games.

"It's huge," Hoskins said of McCutchen's absence. "But it's go time, right? Someone's going to have to step up. Hopefully it's just the 10 days and we can get him right back in there. But the production's going to have to come from somewhere else."

Hoskins hopes to be one of those sources, though it will be at least another day before he's in the starting lineup. He took some swings and fielded grounders on Monday, while also running at a "60-70% clip" without any issues. Girardi said it's possible he'd consider using Hoskins as a pinch-hitter on Monday night.

"I feel close," Hoskins said. "I've definitely made some good progress in the last couple days. The strength is coming back slowly. ... I would imagine that if we continue on that same path that tomorrow I'll be closer to running 100%."

Brad Miller started at first base in Hoskins' absence on Monday, while Odúbel Herrera got the call in left field, with Travis Jankowski in center. Though that's the plan for the immediate future, Girardi did not rule out the possibility of promoting other options -- possibly Mickey Moniak or Matt Vierling -- once Knapp is back up to speed following his return from the paternity list. The team is carrying three catchers for the time being.

"It's possible, but not for today," Girardi said. "We'll continue to evaluate it, but as of today, no, we're not making a move."