The Gunners will be missing injured goalkeeper Petr Cech for the first time in the Premier League this season while defender Laurent Koscielny is also out with a calf injury

The loss of Cech in particular for the biggest game of Arsenal's season is a major blow to their hopes of drawing level with their title rivals.

Stand-in David Ospina was hammered in September for scoring a own goal after dropping the ball beyond his line when he misjudged a corner in the 3-2 defeat by Olympiakos in the Champions League.

He hasn't appeared in the league at all this season and only twice in total since his Champions debacle, with both games coming in the FA Cup.

Yet he is now the man Arsenal must rely on in the absence of the one of the greatest goalkeepers of the Premier League era.

Unsurprisingly, Wenger yesterday gave his full backing to the Colombian. Not that he has much option.

Wenger said: "I have complete confidence in David and I'm not worried at all on that front.

"If you look at the win rate of Ospina it is very good as well."

Cech injured himself after going up for a corner as Arsenal tried to grab a late equaliser in their 2-1 home defeat by Swansea on Wednesday.

PRESSURE: Arsene Wenger

The 33-year-old will be out for up to four weeks, meaning he will miss four league games as well as Tuesday's FA Cup replay at Hull and the trip to Barcelona in the Champions League the following week.

But Wenger refused to blame Cech for a rare misjudgement from the former Chelsea star.

"It is a serious calf injury," he said.

"He had a groin alert on the first goal and he could not kick the ball because of that and maybe compensated a little too much and provoked another muscular injury.

"He declared himself 100 per cent fit.

"Then you have to trust the player. He's 33 years old and he knows his body.

"You want the players to be tough enough to sometimes be able to play through a little pain. You're never completely perfect before a game in March."

Asked if how he felt about Cech's decision to go up for the corner, he added: "I was more frustrated that he didn't touch the ball with his head."

Wenger also tried to pile some pressure on title rivals Spurs and their boss Mauricio Pochettino.

"They have made progress, yes," said Wenger. "Now this is crunch time in the last 10 games and we will see."