Routine pregame running has turned into a fairly major injury for the Red Sox. Saturday afternoon, the team announced closer Craig Kimbrel will be out 3-6 weeks with medial meniscus tear in his left knee. He'll undergo surgery Monday.

Kimbrel suffered the injury during his usual pregame running prior to Friday's game. He did not slip or stumble or anything. Kimbrel felt a tweak during his run and the team sent him for an MRI, which showed the meniscus tear.

The Red Sox will be without All-Star closer Craig Kimbrel for 3-6 weeks. USATSI

Boston added veteran reliever Brad Ziegler in a trade with the Diamondbacks early Saturday morning. He'll be in the mix to close while Kimbrel is on the shelf.

Kimbrel, 28, was selected to his fifth All-Star Game earlier this week, so he'll now have to be replaced on the roster. He is 17 for 19 in saves this season despite a career-high 3.55 ERA. Kimbrel does have 50 strikeouts in 33 innings, however.

The Red Sox are also without setup man Junichi Tazawa, who is nursing a sore shoulder. He has not been placed on the DL but may not be available this weekend. Ziegler figures to step right into a prominent role with his new team. He and Koji Uehara will be in charge of the late innings.

Boston comes into Saturday with 47-38 record. They are in third place in the AL East, two games back of the Orioles and one game back of the Blue Jays. The Red Sox currently sit in the second wild card spot.