The Twins also selected the contract of first baseman/designated hitter Randy Ruiz from Rochester.
Liriano was 10-2 with a 3.28 ERA at Triple-A. A rookie star in 2006, he missed the entire 2007 season because of Tommy John surgery.
Hernandez and Monroe were designated for release or assignment. Hernandez was 10-8 with a 5.48 ERA, and Monroe hit .202 with eight home runs and 29 RBI.
YANKEES: Outfielder Xavier Nady was out of the starting lineup Friday night against the Angels because of inflammation in his right quadriceps.
Nady, acquired from Pittsburgh last weekend, said he was able to run with it, but the team wanted to play it safe.
- Right-hander Chien-Ming Wang , injured running the bases in Houston on June 15, got the cast off his right foot on Tuesday and is expected to be on crutches with a boot protecting his leg for another week. Manager Joe Girardi set Oct. 1 as a possible date for his return.
- Reinstated reliever Brian Bruney (torn ligament in right foot) from the 60-day disabled list.
ORIOLES: Starting pitcher Daniel Cabrera has filed an appeal of his six-game suspension for throwing at the Yankees' Alex Rodriguez .
BRAVES: Brian McCann was cleared for pinch-hit duty on Friday, opening the way for backup catcher Corky Miller to be designated for assignment.
McCann took batting practice and caught in the bullpen before he was cleared by the medical staff. He said he will be available to pinch hit until Monday, when he will start.
Rookie catcher Clint Sammons was in the starting lineup again Friday night.
METS: Right-hander John Maine will skip his next scheduled start to rest his sore throwing shoulder.
Maine (9-7, 4.13 ERA) was diagnosed with a mild strain in his right rotator cuff. Oliver Perez (7-6) will start in Maine's place for Sunday's series finale against Houston.
Dodgers: Made room for Manny Ramirez on the active roster by placing infielder Nomar Garciaparra on the 15-day disabled list because of a sprained medial collateral ligament in his left knee.
PADRES: Khalil Greene went on the 15-day disabled list with a broken left hand, two days after he punched a wall near San Diego's dugout.
REDS: Outfielder Jerry Hairston Jr. (strained right hamstring) was activated from the 15-day disabled list.
The Reds optioned right-hander Todd Coffey to Triple-A Louisville.