Steve Bruce says he did send Jetro Willems on as a central midfielder against Arsenal but changed his mind straight away and shifted him to left wing-back, from where he made the mistake leading to the game's only goal.
There was confusion following the introduction of the Newcastle debutant in the 54th minute as he charged around midfield before being instructed, by Bruce, to change position within 60 seconds.
And Willems was then caught on his heels at the onset of the move which led to Pierre-Emerick Aubameyang's 58th-minute strike.
Bruce said afterwards there had been a 'lack of communication' with the Dutchman and it was assumed he had entered the field without knowing where he was meant to be playing.
However, the Newcastle boss says that was not the case, even though the alternative version does not compensate for the confusion it caused.
'I put Jetro on in midfield, where he played all last season for Frankfurt, and then I very quickly thought, "Do you know something? That's a bit unfair on him",' said Bruce.
'Maybe I should have done it beforehand. It's a bit unfair on him because he's making his debut and (I thought), "I will put him on in his favoured position", so I switched him very, very quickly.
'We've made a mistake, but he wasn't the only one who made a mistake in the build-up to the goal.
'We've made a mistake, two or three people have made that mistake and if you make a mistake in the Premier League, you get punished.
'It's unfortunate, but that's the way it was.'
Meanwhile, Bruce could be without new signing Allan Saint-Maximin for Saturday's trip to Norwich.
'We've got a slight doubt about Allan Saint-Maximin,' he said. 'He's got a bit of a hamstring (problem) and we'll see how he is today (Friday)'.
Newcastle did not win in their first 10 under Rafa Benitez last season, but Bruce knows he cannot afford such a run with the pressure already on.
'I don't think we won until November last year, so it will be vitally important if we can we get a few results,' he said.
'Always, any manager, whatever league you are in, the one thing that takes a little bit of pressure away is to get a few results, so let's hope we can get off and running tomorrow.'