Manager Mike Redmond said the hope was that Yelich would need just a day or two of rest. But Yelich was still experiencing discomfort and was not available Sunday.
Reed Johnson has been filling in for Yelich in left field.
"We have to decide something today or tomorrow," Redmond said before Sunday's series finale with the Pirates.
If Yelich is headed to the disabled list, Jake Marisnick is the likely candidate to get called up from Triple-A New Orleans.
Marisnick and Yelich, close friends, made their MLB debut together last July.
Marisnick, a natural center fielder, can play all three outfield spots. To keep the continuity of the outfield, Marcell Ozuna would most likely remain in center field, although that could change.
In Marisnick's favor is that he is already on the 40-man roster, and he has previous big league experience.
At New Orleans, Marisnick is batting .264 with 11 doubles, three triples, six homers and 27 RBIs.
Yelich is batting .259 with six homers and 24 RBIs, and his 41 runs scored were second on the team to Giancarlo Stanton's 48.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter