Arsene Wenger refused to justify his controversial selection of David Ospina after the goalkeeper’s howler against Olympiacos capped a wretched night for Arsenal.

The Colombian keeper, who started in place of first choice Petr Cech at Emirates Stadium, spilled a corner over the line as the Gunners slumped to their second successive Champions League defeat.

The 3-2 reverse leaves Wenger’s side without a point and facing an uphill battle to qualify for the knockout stages of the competition, with a double header against Group F leaders Bayern Munich next up.

Quizzed about his team selection for Tuesday’s game, the Arsenal boss responded: “I don’t have to give an explanation about every decision I make.

“I make the decisions and selections for the team and I’m responsible for it. You cannot select the team by making a poll before the game.

“Ospina played 19 games last year and kept 14 clean sheets and last week at Tottenham he had a fantastic game [in the Capital One Cup]. It could have happened to Petr Cech as well.

“It’s not because of that we lost the game. We play many games and that is why we rotate – you cannot play every three days without rotating your players, that’s a fact.

“I believe that some aspects of our game were quite good, but we lacked quality in our defensive concentration.

“Olympiacos defended very well, but they had four shots on target and scored three goals.”

Wenger made a total of five changes to the side that had come from behind to triumph 5-2 at Leicester last weekend.

The Gunners conceded first again, with Felipe Pardo’s drive deflecting in off Alex Oxlade-Chamberlain, but Alexis Sanchez set up Theo Walcott to equalise just two minutes later.

Ospina then dropped a Kostas Fortounis corner behind the goal-line as Olympiacos – who had lost all three of their previous Champions League games at the Emirates – regained the lead shortly before the break.

Walcott returned the favour for Sanchez, setting him up for a header to make it 2-2 midway through the second half, only for substitute Alfred Finnbogason to score the winner almost immediately.

It means that the Gunners will go into their home game against Bayern on October 20 bottom of Group F, but the Frenchman insisted his team can still glean enough points to qualify.

“It leaves us in a backward position,” Wenger added. “We have to make a result in our next game. But we are not out of it.”