Last year’s World silver medallists started well against Russia’s Alexandr Nikolaenko and Valeri Sorokina, but after winning the first set they slumped to a 14-21, 21-9, 21-18 defeat in just over an hour.
It puts the pressure on the British pair ahead of two more group matches at Wembley Arena – including a clash with world champions and top seeds Zhang Nan and Zhao Yunlei.
On paper the world number ten pair should have beaten the Russians, who are five places below them on the world rankings.
But they allowed concentration to slip in the second set and their rivals ruthlessly took advantage.
It means they must now beat Germany’s Michael Fuchs and Birgit Michels, the world number 22 pair, on Sunday.
Their final game is a repeat of last year’s world final although they’ve won twice against their Chinese rivals in the last 12 months and will still believe progressing to the quarter-finals, only the top two in each four strong group advance, is in their hands.
"The first set was really good and then it all changed," admitted Adcock.
"We didn't get the advantage that we wanted so it led to them getting it instead.
"We got a great start,we put the pressure on but didn't keep it up. The final game turned into a bit of a scrap and unfortunately we were on the losing end of it.
"It's a round robin so we know we've got two games we can definitely win."
Bankier insisted she was still confident about progressing to the knockout stages, despite the task becoming much harder.
"We're extremely disappointed but we've just got to get over it," she said
"We've still got a chance of getting through. We know we can play better than that so we need to regroup and get through."
"We'll take a few hours, recover, start looking at the video and work out a plan with the coaches, then do it all again tomorrow."
Susan Egelstaff made a confident start to her women's singles campaign with an easy victory in her Olympics debut.
Egelstaff proved too strong for Slovakia's Maja Tvrdy in the first of her three group matches and took just 34 minutes to chalk off the win.
The Scot, a bronze medallist at the 2006 Commonwealth Games and six-time national champion, won through 21-15, 21-10 and faces a two-day break before her next encounter – world number 12 opponent Sayaka Sato.
"I was really nervous because it's such a massive occasion. It started off a little bit scrappy but I feel I've played really well," she said.
"I'm not expecting to get a medal at all but the target in the meantime is just to play well. It's nice not having too high expectations, it means I can just play."
"In such a massive tournament like the Olympics you can't really predict what's going to happen. I definitely wasn't complacent – it was a really nice run.
“It's not getting any easier now with Sato next. I beat her before but obviously she's a much better player now."