London, February 26: Andy Robertson accepts Liverpool have lacked a "spark" as their Premier League title bid stutters.
Jurgen Klopp's men are a point clear at the top after a 0-0 draw at Manchester United on Sunday, although they have now won just one of their past four league games.
Liverpool have scored just five goals in their past five games in all competitions, having also played out a scoreless draw with Bayern Munich last week.
Robertson, whose team host Watford on Wednesday, said Klopp's men needed to improve.
"I can't really remember any real chances , so of course there was a spark missing," he told UK newspapers.
"That's why it's hardest to win a Premier League instead of a Champions League because it's over 38 games. You can't play well in every game but it's about grinding out results.
"We might well look back on these games and say, 'You know what, a time we weren't playing our best we grinded out results and that's what won us the league'.
"There are always times in the season where every team will look at it but we need to start getting back to playing better and attacking better."
Liverpool were unable to find a breakthrough at Old Trafford against an injury-hit United, who had Ander Herrera, Juan Mata and Jesse Lingard come off in the first half.
While Robertson was not satisfied with the result, he was happy the Reds returned to the top.
"It is disappointing, but we are top of the league – and if you'd offered everyone connected to Liverpool being a point clear in February, everybody would have taken it," he said.
"We need to look at the fans, the way they didn't celebrate it but were happy we were back top of the league, happy with the point. We can look at them go, 'You know what, fair play'. But we need to look at that and kick on.
"It's an exciting opportunity that we need to grab with both hands and so at the end of the season we go back and say we gave it our all whether we were good enough or not – as long as we've given it 100 per cent."