The Senegalese frontman has been in excellent form all season, emerging as one of the team's best goalscoring threats.
And Robertson was full of praise for Mane after the game.
"Especially this year he has been fantastic," he told reporters.
"Even when I came to the club [in 2017] he was amazing but maybe did not have as much composure as he does now in front of goal. Now every time he is front of goal you don't think he will miss.
"The one he had at the start of the second half when Hendo put him in, we were surprised he didn't score. That is the type of player he is. You expect him to score and that is a good thing. He has popped up with another crucial goal.
"It has been a fantastic year for him and let's hope he can keep going for a full season instead of a calendar year. That would help. The others are pitching in as well but it's a fantastic year for him and he has taken his game to another level.
"Does he belong in the top bracket? I would say so. People are giving him more credit and that is deserved.
"Our front three gets talked about quite a lot. Maybe Bobby [Firmino] does not score as many as the other two but his work-rate is second to none and if he didn't do what he does, Sadio and Mo [Salah] would not do what they do.
"Hopefully all three can keep going as we are not even halfway through the season and we need them to keep going."