Tazawa is sidelined at a time the Red Sox are also without closer Craig Kimbrel, who will miss three to six weeks following left knee surgery. The recent acquisition of righty Brad Ziegler from the D-backs will help fill the void left by two key relievers, though.
Tazawa, 30, has made 35 relief appearances for the Red Sox this season, going 1-1 with a 3.62 ERA while recording 37 strikeouts and only eight walks. Opponents have hit .215 (26-for-121) against Tazawa this season, with lefties batting just .151 (8-for-53).
This is the third stint with the Red Sox this season for the 25-year-old Cuevas. He has pitched twice for Boston, going 0-1 with a 3.60 ERA over five innings in three appearances. Cuevas is a starter for Pawtucket, where he is 6-3 with a 3.38 ERA over 15 outings.
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.