Brendan Rodgers's side sit second in the Premier League table ahead of this afternoon's fixtures, but have kept just four clean sheets so far this season.
The Dutch defender told the club's official website: "We want to win this, we want to be at the top of the table. We definitely have to win a game like this if that's where we want to be.
"Tottenham are obviously a great team, they have signed some good players. It's going to be a tough game, but we believe in ourselves and we know we can score goals. Now we just need to keep a clean sheet.
"We are attacking a lot this season and that's also why we're scoring a lot of goals. But we have to be better, we have to defend better and keep clean sheets, because that's one of the most important things in football."
Liverpool face Spurs at White Hart Lane tomorrow afternoon.