Manchester United boss Ole Gunnar Solskjaer blasted "unforgivable" defending from his hapless side as they slumped to an embarrassing 2-1 Champions League defeat against Istanbul Basaksehir on Wednesday. United, floundering in the lower reaches of the Premier League, started the game as firm favourites after an impressive win against Paris Saint-Germain and a 5-0 humbling of RB Leipzig. But defeat in Turkey -- a first-ever Champions League group-stage win for Basaksehir -- heaps the pressure on the Norwegian boss, whose side looked short of inspiration and basic defensive nous in Istanbul. The three-time European champions were badly exposed on the break as former Chelsea forward Demba Ba and Edin Visca gave the home team a two-goal cushion.
United gave themselves hope when they reduced the deficit shortly before half-time through an Anthony Martial header.
But despite multiple second-half changes and an array of attacking talent, Solskjaer's lacklustre team could not find a way past the organised Basaksehir defence.
The result ended Manchester United's longest away winning run in all competitions in their history -- 10 straight victories -- and was their first away defeat in 19 matches since losing in January at Liverpool in the Premier League.
Solskjaer said the performance against the hard-working Turkish side was not good enough.
"They scored two goals like you do in Europe when you do not defend well enough," he told BT Sport.
"The first one is that we play a short corner and forget about the man up top. That is unforgivable. The second one as well, we are not very well organised to counter the press."
"You don't turn up and get three points in the Champions League," he added. "They are a team well organised and we were not good enough. That is it."
- Defensive chaos -
United started the game in the comfort zone, with no sign of the defensive chaos to come in front of a small but vocal crowd.
Luke Shaw fizzed a ball past the far post with his left foot but United, with Marcus Rashford and Martial up front, lacked penetration.
The home side were ahead in the 12th minute after inexplicably poor awareness and organisation allowed unmarshalled ex-Chelsea forward Ba to collect a long ball and race from the halfway line to score, trailed helplessly by Nemanja Matic.
Axel Tuanzebe, who impressed in Paris, had a heart-stopping moment after he pulled Ba back but escaped with a yellow card.
Basaksehir remained threatening on the break, with United worryingly open at the back, and the visitors were caught napping again five minutes before half time.
Deniz Turuc robbed Juan Mata of possession down the left and raced forward, sending over a cross that Ba stepped over and Visca smashed past Dean Henderson, making his Champions League debut in place of David de Gea.
United crucially reduced the deficit in the 43rd minute when Martial steered a Shaw cross home with his head.
Solskjaer hooked off Tuanzebe at the interval, with Scott McTominay coming on and Matic dropping back to play at centre-back alongside Harry Maguire.
United once more enjoyed territorial advantage at the start of the second half and Bruno Fernandes had a free-kick pushed away.
Solskjaer threw on Edinson Cavani and Paul Pogba in place of Mata and Donny van de Beek to add impetus to the attack but ponderous United struggled to create clear chances.
Mason Greenwood came on for Rashford as United continued to search for a way through.
They went agonisingly close to an equaliser in stoppage time when Alexandru Epureanu hacked off the line but they could not rescue a point in the Group H tie.
United appeared to have turned the corner after their 6-1 mauling by Tottenham last month but they have now suffered consecutive defeats to Arsenal and Basaksehir.
"They (two losses) have set us back a lot," said Solskjaer, whose team travel to Everton on Saturday. "You get a reality check every time you play a game of football."