Eddie Howe said he remains fully committed to his role as Newcastle manager but must reflect on his own performance after a damaging 2-1 derby defeat to Sunderland compounded a miserable week for the Magpies.
Newcastle were humbled 7-2 by Barcelona to bow out of the Champions League in midweek and failure to end a barren spell over Sunderland in the league saw them slip behind the Black Cats and down to 12th in the Premier League.
Sunderland have still not tasted defeat in a league game between the sides for 15 years as they stretched a club-record unbeaten run in the Tyne-Wear derby to 11 matches.
"Very, very painful. Most of all painful for our supporters and they're the ones I think about now," said Howe.
"I've got very little to use as an excuse. Once you haven't performed and you know how much the game means you have to accept the criticism."
Newcastle were booed off at full-time after a performance that will put Howe's future under scrutiny.
He has twice delivered Champions League football and won the club's first domestic trophy for 70 years since being appointed just under five years ago.
But despite the resources of the Saudi sovereign wealth fund behind them, Newcastle's progress has stalled due to poor recruitment and having to meet financial sustainability rules.
"I understand the reaction at the end of the game," added Howe. "I'm fully committed (to the job). I'm disappointed in myself and my delivery over the last week."
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Anthony Gordon's strike after 10 minutes had given Newcastle the perfect start.
But their exhausting schedule over recent months caught up with them after the break.
No side in Europe's top five leagues have played more games than Howe's men this season, but their campaign is in danger of fizzling out to an anti-climatic finish.
They remain seven points adrift of the Champions League places, but Howe is hoping that a lighter schedule after an upcoming international break will aid their chances of European qualification.
"We've got some massive games to come in the Premier League," said Howe.
"We get a chance to go into a diferent phase of our season where, week-to-week, we're able to train and maybe get that freshness back in our performance."
Sunderland's victory was also marred by a report of racist abuse aimed at Lutsharel Geertruida.
Play was briefly stopped during the second half after the Dutch defender reported the incident to the officials.
"We are aware of a report of racism made by a visiting player against someone in the crowd during our Premier League match against Sunderland," Newcastle said in a statement.
"Our stance is clear - we do not tolerate discrimination of any form. We will work with the authorities to fully investigate and will ensure any individuals are identified and held accountable."