"Left-hander Zach Duke is likely to miss two months with two fractured bones in his pitching hand, creating an opening in the Diamondbacks rotation that General Manager Kevin Towers expects to fill internally.

Duke was struck by a line drive off the bat of Colorado's Charlie Blackmon during the second inning Saturday night and found out from hand specialist Dr. Don Sheridan on Sunday morning that the injury was more serious than he expected.

"It was very sensitive in the area, but I'm kind of surprised there's two broken bones in there," he said. "I'm going to shoot for as short a recovery as possible. The bones will tell me how much time it's going to take. The doctor wanted me to have X-rays each week to keep track of how it's healing. I'm going to be optimistic for sure."

Duke was penciled in at the back of the rotation, so the Diamondbacks will have to turn elsewhere. The most likely replacement looks to be right-hander Barry Enright, who posted a 3.91 ERA in 17 starts last season and has given up just two runs in nine innings in the Cactus League.

"He's been throwing the ball well," Towers said. "He's thrown the ball well all spring and threw the ball well at the end of last year."

Right-hander Aaron Heilman also is said to be competing for a spot in the rotation, but at this point, he appears to be behind Enright and Armando Galarraga in the pecking order for the last two rotation spots - and thus likely to return to the bullpen."