Bryce Harper sliding into third base on Friday night. (Nick Wass/Associated Press)

Nationals left fielder Bryce Harper received an MRI exam Saturday afternoon on his swollen left thumb, Nationals Manager Matt Williams said, raising the possibility that Harper could be headed to the disabled list.

While the Nationals had not received results as of late Saturday afternoon, the MRI could be an indication he suffered more than a minor injury. Harper visited a hand specialist Saturday during the National’s 4-0 victory over the Padres, and the specialist deemed the exam necessary to find out if something deeper could be wrong, potentially with a ligament in Harper’s thumb.

During the game, television cameras spotted Harper talking to Williams in the dugout with a small kind of cast or splint on his left hand.

If Harper lands on the disabled list, outfielder Steven Souza Jr. would be the likeliest candidate to take his roster spot. Souza was not in the lineup at Class AAA Syracuse on Saturday, and he was not used in a situation that would have typically called for a pinch hitter.

Williams said he expects Harper to miss Sunday’s game. The Nationals do not play Monday. Before Saturday’s game, Williams said Harper was available off the bench. Following the victory, Williams clarified, saying that Harper was perhaps less likely to play than it appeared.

“Emergency situation, down to the last guy, extra innings, stuff like that,” Williams said. “But he’s going in for an MRI right now to have it looked at. Such a quick turnaround, it’s hard to get him in. So we had to wait till the end of the game.”

Harper initially underwent an X-ray Friday night, and those results were negative, Williams said. He said the MRI was standard procedure, and the hand specialist was in Washington to see Ryan Zimmerman (fractured thumb) and Wilson Ramos (hamate bone surgery), anyway.

“We wanted to make sure,” Williams said of Harper’s MRI. “It could’ve been done (Friday) night, but you have to make special arrangements. He probably wasn’t going to play (Saturday) anyway.”

Harper hurt his thumb Friday night when he slid headfirst into third base after a triple that gave the Nationals a 5-0 lead. Harper remained in the game for an inning in left field.

If the injury proves to be serious enough, Harper will land on the disabled list for the second straight season. Last year, Harper missed 31 games with bursitis in his left knee, an injury he played through for much of the season and had repaired with offseason surgery.

The Nationals have already lost Ramos, Zimmerman, starter Doug Fister and reserve outfielder Scott Hairston to injuries that will cost them all at least a month.