The Reds are looking to defend the Premier League title they won last term, which was achieved at a canter.
While they are still title favourites and top of the table this term, it looks as though it will be a lot more difficult for Liverpool.
And after a slim win over Tottenham, Robertson knows they will have to slog all season to win the title.
He told the club website post-game: "When you play against a big team, obviously top of the league – they were first going into this game – scoring a last-minute winner is big. All the lads felt it.
"But it's only big if you use it in the right way and you try to kick on from it. We're top of the league for tonight but there's still a long, long way to go.
"But it's a big win against a really, really good team. We created good chances, we dominated the ball first half; the second half was a bit more even.
"We've beaten a good team tonight and it's always nice when you do that. But they'll be there, they'll come back again and we need to be at our best every game to stay top now because there's a lot of teams trying to catch us, it's a lot closer race this year and it will go the whole way.
"We just need to keep doing what we're doing, focus on us and keep picking up three points as much as we can."