As the Philadelphia Phillies potentially close in on their first playoff appearance since 2011, they may be even further depleted.

Already without catcher J.T. Realmuto, first baseman Rhys Hoskins, starting pitchers Spencer Howard and Jake Arrieta and reliever Jose Alvarez, the Phillies receivedanother dose of bad news in Sunday's 6-3 loss to the Toronto Blue Jays.

Bryce Harper left the game with back tightness after striking out in the seventh inning, and his status is questionable for Monday's road game against the Washington Nationals and beyond.

Phillies manager Joe Girardi didn't offer a concrete time frame for Harper, saying it's "something he's dealt with from time to time."

The Phillies took three of four from the Blue Jays and sit at 27-26 heading into the start of this four-game series against the Nationals.

Philadelphia will turn to right hander Zack Wheeler, who's 4-0 with a 2.62 ERA in nine starts this season. For Wheeler's career, he's 6-10 with a 4.71 ERA in 19 starts against the Nationals.

Wheeler has been hampered by a fingernail issue on the middle finger of his pitching hand, but he has dealt with this off and on throughout his career.

Wheeler allowed seven hits and three runs in 7 1/3 innings in his last outing against the New York Mets.

"It gives us confidence moving forward that this finger thing is behind us," catcher Andrew Knapp said after Wheeler's last start. "He's one of our horses. We're going to have to ride him all the way through."

Wheeler had trouble locating his changeup because of lingering pain from the nail. Yet he battled through. And he'll continue to do that.

"Just the pressure of the changeup bothered me a little too much," Wheeler said. "So I just moved onto the split, and it was a really good pitch."

The defending World Series champion Nationals have struggled for much of the season, but managed a 15-0 blowout in the second game of a doubleheader Sunday against the Miami Marlins.

Trea Turner, Kurt Suzuki, Michael A. Taylor, Asdrubal Cabrera and Victor Robles each homered against the Marlins.

Still, the Nationals are 20-32 with eight games left.

"It's definitely frustrating how we've played so far this season," pitcher Patrick Corbin said. "I know guys have been working their butts off to try to go out there and win games."

Like the Phillies, the Nationals have been besieged by injuries losing key players such as Tanner Rainey and Howie Kendrick along with pitchers Stephen Strasburg and Sean Doolittle, among others.

One of their scuffling pitchers, Anibal Sanchez, will start the opener on Monday.

Sanchez will enter this game with a 2-5 record and a 7.38 ERA in what will be his 10th start.

For Sanchez's career, he's 6-11 with a 4.48 ERA in 26 starts against the Phillies.

Sanchez allowed seven hits and six runs in 4 1/3 innings in his last start against the Tampa Bay Rays and simply never found his rhythm despite heading into the game with a lot of confidence.

"I felt really good early in the game," Sanchez said. "I finally figured out my mechanics and how to make the hitter miss my fastball. My changeup even started breaking good out of the strike zone."