DENVER -- The Reds learned more about starting pitcher Nick Lodolo's leg injury this week, and the news was not good. 

A follow-up MRI taken on Monday revealed that Lodolo has a stress reaction in his left tibia. He is expected to be in a walking boot for at least two weeks and then undergo another MRI to track the progress. It's looking like a more long-term absence from the rotation is ahead for the left-hander.

"He’s still at the beginning stages of being in a boot and letting it heal. He’s pretty limited right now," Reds manager David Bell said. "Limited him on purpose, so he can heal before he takes any next steps. I think the next big milestone will be another MRI in two weeks. At that point, if he’s made progress, we’ll know a lot more about what the overall timeline is going to be."

Lodolo, who pitched through soreness in his left calf during Spring Training, was given new orthotic inserts for his spikes recently to no avail. He was originally diagnosed with left calf tendinosis when he was scratched from a start at Miami and placed on the 15-day injured list on May 14.

In seven starts this season, the 25-year-old Lodolo is 2-1 with a 6.29 ERA. He started the season strong, however, with a 2.12 ERA through his first three outings -- including a 12-strikeout performance over seven scoreless innings vs. the Phillies on April 8.

Struggles began after that, and Lodolo posted a 10.38 ERA over his last four starts.

Lodolo's injury, combined with the recent release of Luis Cessa, had Cincinnati's rotation shorthanded. In the past week, they used an opener twice for what were largely bullpen days. 

Although a starter normally, Ben Lively was one of the pitchers who has worked successfully out of the bullpen since his May 9 promotion from Triple-A Louisville to replace Cessa on the roster. Lively, with a 1.69 ERA through two appearances, is joining the big league rotation on Friday to pitch against the Yankees. 

The Reds also got a boost from left-handed pitching prospect Brandon Williamson on Tuesday. Williamson, the organization's No. 10 prospect according to MLB Pipeline, made his big league debut with 5 2/3 innings with one run and two hits allowed for a no-decision during a 3-1 victory over the Rockies. He is also expected to stay in the rotation for the time being.

Cincinnati will also continue to monitor the work of another lefty at Louisville in No. 6 prospect Andrew Abbott. He is 2-0 with a 3.03 ERA in seven starts combined for Double-A Chattanooga and Louisville. Abbott could get consideration for his first big league promotion in the coming weeks.