The Reds will face City in the FA Cup semi-final this week, while they are favourites to reach the Champions League semi-finals ahead of Wednesday's quarter-final second leg against Benfica.
"We can only focus on ourselves," Robertson said. "I think we have got a really tough run-in, all games are tough in the Premier League especially when you get to the end bit.
"But we have some really tough games and we need to try win them, we need to be at our best, we need to be better than we were (on Sunday) and if we do that then let's see where we end up.
"We just need to keep winning games. We had to do it (in 2019) and we have to do it this year. It's obviously out of our hands, if they win all their games then it is their league but if they do drop points we need to be ready to pounce.
"Will we need win every game? Time will tell. You never know. We need to win as many games as it takes, it's as simple as that. We wait to see what results happen, we need to keep dealing with each game as it comes."