Cech ruled out of Tottenham match with injury.

Arsenal goalkeeper Petr Cech will now miss the highly anticipated North London derby against Tottenham after picking up an injury near the end of the 2-1 defeat to Swansea on Wednesday.

Cech looked to be clutching his hamstring after he ran up for an Arsenal corner in the final minute of injury time as the Gunners were desperate for an equaliser, and Arsene Wenger later revealed he has a “muscular problem.”

“He had a little groin problem before the game, and I think he struggled a bit today,” Wenger said. “He will not play on Saturday. … I do not know for how long he will be out.”

That means David Ospina will have a rare chance of league start in one of the most important fixtures remaining in this season, with Arsenal still three points behind Tottenham ahead of this weekend’s encounter at White Hart Lane.

Ospina has just featured in two FA Cup matches since his blunder helped give Olympiakos a 3-2 win in the Champions League back in September.

“I trust Ospina completely, I have no problem with that,” Wenger insisted.

With Arsenal and Tottenham both chasing league toppers Leicester in the Premier League title race, Saturday’s fixture assures to be the most important North London derby in years.

Not only Cech, Arsenal will also miss Laurent Koscielny for the clash. The centre-back didn’t play in Wednesday’s game with a calf injury, and Wenger has admitted he will not be fit by the weekend.

“He will not play on Saturday as well,” Wenger revealed.

Arsène Wenger also admitted his players were somehow suffering from a confidence issue after Arsenal slumped to a 2-1 defeat at the hands of Swansea which hammered their Premier League title aspirations in front of a baying home crowd. It appears the Gunners weren’t able to bounce back from Sunday’s 3-2 loss at Manchester United. It also triggered a sense of crisis which ultimately saw how the nervousness of the players and their supporters made for a damaging combination.

Wenger’s boys at first led through Joel Campbell but they were hammered by goals from Wayne Routledge and Ashley Williams, which actually allowed Swansea to celebrate a crucial win in their fight against relegation.

Arsenal’s third consecutive defeat, and second in four days, means they have now won only two of their last eight fixtures in the Premier League and four in 12 in all competitions.