Keane declared last month suggesting he "wouldn't watch Liverpool if they were playing in my back garden" generating plenty of debate.
"Clearly they're beating these so-called lesser teams, and the same in the Premier League, but they've beaten nobody yet, domestically and in Europe yet," said Keane in his role as an ITV pundit.
"The big tests are yet to come for Liverpool. They are certainly in great form at the moment, but the bigger teams are still to come.
"Going forward it's lovely to watch when they play well, but they wouldn't get that time and space against the decent teams, it's as simple as that. Give quality players time on the ball and they will punish you, but they won't get that time and space against quality teams."