The Rockies have yet to make an official announcement.
Matsui, 35, signed with the Astros after hitting .300 in a Rockies uniform in 2006-07. He put up strong numbers in an injury-shortened 2008 with the Astros, but declined last season (.250 BA, 9 HR, 46 RBIs) and hit .141 in 27 games this season before being released last Wednesday.
Matsui cleared waivers on Monday.
If Matsui passes his physical -- back injuries have bothered him for years -- he will go to the Sky Sox to stay sharp and provide infield insurance for the Rockies.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.