Jennings bunted for a hit to lead off the inning but was visited by trainers soon after and pulled from the game. Sam Fuld replaced Jennings, advanced to third on a walk and a wild pitch, and scored on Matt Joyce's sacrifice fly.
"The tip was [that] the pitcher was really slow to the plate, and [Jennings] did not want to run," manager Joe Maddon said. "I went out there and said, 'I don't want you to get hurt, and I want to run on this pitch.' That's when we put Sam in, and he ends up going first to third. That's why players have to be honest with you, for the team and for their own benefit."
Jennings had been scratched from Friday's lineup because of stiffness in his neck but entered in the ninth inning and scored the winning run of the 18-inning contest. He played all nine innings in center field on Saturday.
Maddon is hopeful the strain is not a significant one.
"Desmond has been playing well, and I know that's why he wanted to stay out there," he said. "Everything has been rolling for him, but let's hope it's very minor."