Arsenal’s hopes of Champions League progress are in serious jeopardy after they slumped to their second successive group stage loss at home to Olympiakos. Arsene Wenger’s side knew nothing other than victory would do after defeat by Dinamo Zagreb in Croatia in their opening game – and with two meetings with group favourites Bayern Munich still to come. Instead it was a dreadful night for Arsenal, who must now become the first team since Galatasaray in 2012-13 to lose their first two group games and still reach the knockout stage. The Gunners’ display was summed up by the wretched first-half own goal conceded by David Ospina – preferred to Petr Cech in goal – when he dropped Kostas Fortounis’s corner into his own net after Theo Walcott equalised Felipe Pardo’s deflected shot.

Alexis Sanchez gave Arsenal hope with a 65th-minute header only for Alfred Finnbogason to restore Olympiakos’s lead within a minute. When Arsene Wenger persuaded Chelsea to sell them goalkeeper Petr Cech, the theory behind his arrival was that the 33-year-old’s experience, wisdom and acquaintance with success would make the difference in the big games. So what sense did it make for Wenger to leave Cech on the bench and select his deputy Ospina for a game where Arsenal simply could not risk any mistakes or the concession of cheap goals? Forget talk about any slight injury to Cech. He was fit enough to take his place on the bench so surely fit enough to start a game of this significance. Fate was tempted – and could not resist as the hapless Colombian dropped a harmless corner from Fortounis into his own net just before half-time after Walcott had brought Arsenal back into it with an equaliser.

Wenger’s decision was laced with high-risk – and in the context of Arsenal’s hopes of making progress in the Champions League a risk not worth taking, as well as a serious error of judgement. Arsenal were victims of a deflection and a crass goalkeeping error for Olympiakos’s first two goals – but the soft underbelly was on show again for the third, so easily unpicked as Finnbogason steered in the winner. Amid a night of unrelenting gloom, the only shafts of light for Arsenal and their supporters were Walcott and Sanchez. The Englishman continued his development as a striker with another goal, his second in successive Champions League games after scoring his 12th in 13 Premier League matches at Leicester City on Saturday. Sanchez scored a hat-trick at Leicester and he was lively throughout, heading the second equaliser only to see Olympiakos score their third almost immediately. In reality, this is to clutch at straws because this was a desperate Arsenal display elsewhere.