With Monday being an off-day for the team, Uehara will be examined by team doctors in Boston on Monday.
If that exam goes as the Red Sox hope, Uehara will rejoin the team for the start of a three-game series in Chicago.
"During the time he was throwing, he felt better than he actually expected. He's still going to return to Boston to go through a full work-up tomorrow," said Farrell. "At this point, we're hopeful and expecting him to return to us in Chicago. We'd still like to get him off a mound in a bullpen session or get him back in a game, but today, overall, was very good news regarding Koji."
What did Uehara do during Sunday's throwing session?
"He threw long toss out to 200 feet, and came back in at roughly 65-70 feet, and was aggressive on flat ground with both his fastball and his split," said Farrell. "He was really able to generate good arm speed. He's moving past some of the concerns, mentally, that he had. A bullpen session is certainly going to be needed and helpful to get past that further."
Ian Browne is a reporter for MLB.com.
This story was not subject to the approval of Major League Baseball or its clubs.