Liverpool midfielder Javier Mascherano admits he cannot explain how they allowed Arsenal to beat them earlier this season.
The Reds go to London tonight to face the Gunners.
Mascherano believes he and his team-mates are ready to cause Arsene Wenger's men significant problems.
"If you remember, in the first half they didn't kick to our goal," said Mascherano, shaking his head at the memory to the Liverpool Echo. "So it is difficult to explain how this team can go and play two different halves. It's almost impossible to explain.
"We conceded an early goal in the second half and then they kept coming at us. But in football, I always say it is 80 per cent mentally, the other 20 per cent is physical and tactically. If a player has confidence, it is easy for the team."