Chelsea boss Jose Mourinho says the Premier League has become much more competitive than during his previous spell in England.
Liverpool's revival is one of the many aspects of change Mourinho has encountered on his return after a near six-year absence.
He said: "The top four has become a problem that didn't exist before.
"In this moment you start the season and all the big teams are at risk over finishing in the top four. That becomes fundamental, not just for the economical aspect.
"For the teams that respect Financial Fair Play, finishing in the top four is very important, because it's financially crucial.
"Also by the prestige point of view and to try to attract the best players and the best sponsors to finish top four is really, really important.
"I don't think a club can afford to be two or three consecutive years out of the top four.
"Now it's a real problem with City becoming an economical force, Liverpool coming up. Now it's much, much harder."
