Mauer, on the disabled list since April 14, has hit .235 in the first season of a $184 million, eight-year contract. He had arthroscopic surgery on his left knee in the offseason and only played sparingly in spring training.
Assistant trainer Dave Pruemer said Tuesday there is no timetable for Mauer's return but the catcher is over much of the soreness in his legs and feels stronger.
Minnesota is 10-18 and in fourth place in the AL Central after Liriano threw the season's first no-no and the seventh in franchise history, which pushed Chicago a half-game behind the Twins and into the division cellar.
"We've done it before but we always had the other pieces in place," manager Ron Gardenhire said of Minnesota's rough start. "It's always tough going without your catcher and your three-hole hitter and all those things. That's never been an easy thing to replace or fill that hole. But when you have all your other parts working around it, it makes it a little easier to try to get through things. This has been really tough."
Right-hander Kevin Slowey, on the disabled list since April 9 because of bursitis in his throwing shoulder, threw about 65 pitches in his last rehab outing and could join the team when it goes to Boston this weekend. He likely will be in the bullpen.
Thome, who has 591 career homers, was placed on the 15-day disabled list retroactive to May 1. He had missed five of the last six games with the oblique injury.
The Twins recalled infielder Trevor Plouffe from Triple-A Rochester. Plouffe will to join the team in Chicago for Wednesday's game against the White Sox.
Information from The Associated Press was used in this report.