And at today's (Thursday), press conference, Yems said that he would be out for three months.
The gaffer said: "Caleb is out for three months.
"He played 17 minutes bless him and I spoke to him this morning and he may have to have surgery. Southampton have been decent with it and they are dealing with it at the moment and I will sort it out with them when I get out of this press conference."
And Yems said this was the kind of luck his side were having this year.
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He said: "This is the the sort of thing we are having. We lost Tom [Nichols] at the start of the season, we lost Jordan [Tunnicliffe] and other key players from last year. Jake Hessenthaler is out now."
Kwesi Appiah and Ludwig Francillette are also among those on the sideline.
With Watts out for a while and still time left until deadline day, we asked Yems whether they would be dipping into the loan market again.
He said: "I don’t think we can go around the fruit market let alone the loan market. I don’t know the answer.. I would like to think we would but I don’t know."
Reds are at home for the first time since New Year's Day on Saturday when they host Tranmere Rovers.