Both Klopp and the Liverpool first team having come under intense criticism during recent times following the clubs frustrating start to the season during which their defence in particular has been poor.
And Nicol believes that the German will be sacked should they fail to qualify for the 2018/19 Champions League.
He told ESPN: "No (he shouldn't get sacked at the end of the season).
"But I would suggest that the following season, if it's the same thing, then yes (he should get sacked)."
"Yes (I'd give him 18 months)."