The righty reliever has been out since July 20 with a right pectoral strain. It is an unusual injury for a pitcher, making it hard for the Red Sox to put much of an estimate on a return date.
Uehara has been playing catch at a distance of 90 feet.
"He'll increase the distance and the volume based on tolerance," said Red Sox manager John Farrell. "I think these early throwing sessions have been encouraging to date."
But Uehara knows he is up against the clock, with just 49 games left in the season.
"I'm far away from my peak performance or the best I can be," said Uehara. "All I can do is work every day and try to get better."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.