After a club record 68-match unbeaten run at home in the league, the champions have now lost back-to-back home matches against Burnley and the Seagulls.
“Any game against Man City is a big one. As this moment stands, we're not in the title race," admitted Robertson.
"We are seven points behind them and they have a game in hand.
"I'm sure they'd say the same if they were potentially 10 points behind. We need to get back to the Liverpool everyone knows.
“We're still a good team. We don't turn into a bad team overnight."