(Photo by Greg Fiume/Getty Images)

Nationals third baseman Ryan Zimmerman exited the Nationals‘ game Tuesday night against the Rockies after he appeared to pull a muscle in his right leg while running down the first base line. Zimmerman has already missed 44 games this season with a broken thumb, and given the ugly manner in which Zimmerman tumbled to the dirt, he may well be headed back to the disabled list.

Trying to beat out a 6-4-3 double play, Zimmerman stumbled as he neared first base after his right leg gave out. Zimmerman stepped on first base and fell to the ground, his right leg stiff, Zimmerman careful not to bear any weight with it. He collapsed to the ground face first. Zimmerman quickly rolled over, sat up and summoned the dugout.

Manager Matt Williams and head athletic trainer Lee Kuntz jogged to first base. After a brief chat, Zimmerman hobbled off the field with his arm around Kuntz’s shoulder. He limped down the dugout steps with difficulty, unable to place any weight on his right leg.

It has been a season of sacrifice for Zimmerman. He changed positions the first time he came off the disabled list, moving to left field after nine seasons spent as a pillar at third base. When Bryce Harper returned, Zimmerman moved back to third base, a position that tests his battered right shoulder. He risked embarrassment in multiple ways for the betterment of his team.

He also became a major cog in a lineup firing at full capacity with renewed health. Since June 17, Zimmerman has hit .312/.376/.505. The Nationals this season are 33-19 with Zimmerman and 21-24 when he does not play.

Danny Espinosa replaced Zimmerman once he left Tuesday night. He played second, and Anthony Rendon moved to third to take over Zimmerman’s position.