He told the official website: "We do know that Ben has damaged the cruciate ligament and the only thing we're not sure about is how long he'll be out for.
"It looks like he'll be at least between six and eight months and of course, we're all deeply disappointed for Ben."
The immediate problem for Taylor is that he'll be missing his top goalscorer for the final two games of the run-in. Stuart Elliott may be shifted up front, while Jon Walters or Jamie Forrester could also be recalled to partner Danny Allsopp. Taylor will have his fingers crossed that Jason Price recovers from his hamstring injury before the end of the season to increase City's attacking options.
Elsewhere, Delaney missed training with a bruised foot and Walters has pulled out of the Republic of Ireland Under-21 squad due to illness, but both should be fit for Saturday's game at Yeovil.