Arsenal manager Arsene Wenger confirmed that injured goalkeeper Petr Cech could be sidelined for three to four weeks with a calf injury as he said that the team's confidence was "jaded" after Wednesday's game.
Speaking ahead of the pivotal North London derby on Saturday, the Frenchman described Cech's injury as serious, and added that Laurent Koscielny will also miss the White Hart Lane match with Tottenham.
He said: "It is a serious calf injury and he had a groin alert on the first goal and he could not kick the ball properly out because of his groin and maybe compensated a little too much and provoked another muscular injury."
But he added that he had "complete confidence" in David Ospina who will deputise for Cech at Spurs and in the coming weeks.
On tomorrow's game, he said that the result is difficult to predict, adding that their confidence was "jaded" after Wednesday's loss to Swansea City.
"The results are so unpredictable, the most gifted mathematician will have problems working out how this Premier League works," he said.