Matthews was removed from Friday's game against the Brewers with an apparent injury, Dan Hayes of The Athletic reports.
The Twins designated Rashi for assignment Friday.
The Twins selected Culpepper's contract from Triple-A St. Paul on Friday.
The Twins placed Ryan on the 15-day injured list Friday with a left glute strain.
Vivas is not in the lineup for Friday's contest versus the Reds.
Ruiz is not in the lineup for Friday's game versus the Reds.
Alvarez is slated to start Saturday's game against the Reds at Nationals Park.
Pinckney went 1-for-2 with a solo home run in Thursday's 7-3 loss to the Phillies.
Perales is a pitcher the Nationals believe is nearly ready to make his big-league debut, Spencer Nusbaum of The Athletic reports.
The Twins will call up Culpepper from Triple-A St. Paul prior to Friday's game in Milwaukee, Aaron Gleeman of AaronGleeman.com reports.
