Man United let two-goal lead slid in classic match with Galatasaray
Onana's poor attempt to stop Hakim Ziyech's free-kick got Galatasaray back in the game before half-time
Manchester United's Champions League hopes suffered another setback as a horror show from goalkeeper Andre Onana allowed Galatasaray to earn a draw in a classic match in Istanbul.
Erik ten Hag's side did so much right and twice held a two-goal lead but errors from Onana threw Galatasaray lifelines to leave United bottom of Group A with their hopes of reaching the knockout phase in the balance before their final game at home to Bayern Munich.
After Bayern Munich's draw with Copenhagen later in the evening, Manchester United will be knocked out of the competition if they fail to beat the German champions and there is a winner between Galatasaray and Copenhagen in a fortnight.
United, as they did in their last Champions League game in Copenhagen, were in a commanding position early on after superb strikes from Alejandro Garnacho and Bruno Fernandes inside the first 18 minutes.
Onana's poor attempt to stop Hakim Ziyech's free-kick got Galatasaray back in the game before half-time but United looked to have gained control again in what was a hostile atmosphere when Scott McTominay turned in Aaron Wan-Bissaka's cross 10 minutes after the break to make it 3-1.
However Ziyech was gifted a second goal from another free-kick after an even more stark blunder from Onana, who made a hapless attempt to keep the ball out, before Galatasaray substitute Kerem Akturkoglu's explosive finish brought them level with 19 minutes left.
In a dramatic end-to-end finale, Wilfried Zaha missed a glorious chance for Galatasaray and Fernandes struck the upright as United's Champions League destiny was taken out of their own hands.
Man Utd left to lament Onana blunders
United saw history repeat itself - and not in a good way - as they were left to regret squandering yet another strong Champions League position to leave their hopes of reaching the last 16 in serious jeopardy.
They ended up losing 4-3 in Denmark after scoring two early goals to assume control against Copenhagen. This time the finger of blame is directed at goalkeeper Onana, who understandably looked disconsolate as the final whistle sounded on a stormy night on the pitch and overhead in Istanbul.
United were looking composed with those early goals from Garnacho - with another spectacular finish to add to his moment of genius at Everton - and Fernandes, before Onana got his positioning hopelessly wrong to allow Ziyech's routine free-kick to slide in after 29 minutes.
So much of United's work on the night was good though, and they responded well when McTominay slid in their third.
Only Onana will know what he was doing with his attempt to keep out another Ziyech free-kick just after the hour mark, the keeper merely helping his straightforward delivery into the net, to give Galatasaray the impetus for Akturkoglu's blistering equaliser.
Since 2018-19, he has made the most errors leading to opposition goals by goalkeepers in the Champions League, with seven costly mistakes.
In a chaotic and highly entertaining conclusion, both sides streamed forward in search of the winner that could have proved vital and it was incredible there was not another goal given the number of opportunities.
Instead, United were again left to regret their failure to see out a game they were in command of, with another poor display from the goalkeeper they signed from Inter Milan principally at fault.