The Frenchman was substituted in the first half at BMO Field after sustaining the injury and was missing from training on Wednesday.
“We lose over that time period a guy with a lot of experience, a guy who in a lot of situations you can call upon,” Greg Vanney said after confirming that Cheyrou would be sidelined.
“Any time you’re missing a player with his level of experience and knowledge, you feel that. But like everybody else, it means that someone is going to have to step up and provide us with some depth and cover in that position.”
Cheyrou’s injury is undoubtedly a blow. He is Toronto’s best cover for Michael Bradley at the base of midfield and has also shown well off the bench in a more advanced role on one or two occasions this season.
Bradley has tended to play every minute when healthy and it is feasible, given the way the schedule lightens from this point onwards, that he will not be taken out of the lineup - or even be substituted - between now and the end of the season.
The problem, of course, is that if the captain at any point struggles with the kind of niggle that could benefit from a game or two off, Toronto will be short of natural holding midfielders that can relieve him.
Then there is the worst-case scenario of Bradley going down for an extended period of time - though I would suggest that in that case, with no disrespect to Cheyrou, his presence would only soften the blow of fairly disastrous news anyway.
Marky Delgado has played in front of the defence before with some success but prefers a role as a box-to-box midfielder and has become increasingly influential in that position this year.
Beyond that, there is not a lot.
It is not out of the realm of possibility that general manager Tim Bezbatchenko will dip into the transfer market before the August 9 deadline to add some extra cover.
Toronto looked set to do that in the event Steven Beitashour was ruled out for the remainder of the season following his pancreas surgery by bringing in Brazilian right-back Raul Cardoso on trial, but Beitashour has now resumed light workouts and Raul has returned to Gremio.
That would suggest the Reds have the salary-cap flexibility to add a player - potentially on a loan deal - if they judge they need one.
Normally, Toronto would probably hope they can cope without Cheyrou but finding themselves right in the middle of their MLS Cup window as they do, there is clearly a desire not to take any chances or have any regrets this December when it comes to squad depth.