Newcastle boss John Carver fears his side's 1-0 defeat by Sunderland will define his reign at St James' Park.
Newcastle were beaten by a spectacular goal from Jermain Defoe and have now lost their last five Tyne-Wear derbies.
Carver, head coach until the end of the season, said: "We are down to the bare bones but we should come to a stadium like this and do better than we did.
"It will define my spell in charge. It's not nice so I will suffer for a few weeks, months, possibly years."
Carver said he felt that - a makeshift back four and goalkeeper Tim Krul excepted - his Newcastle side did not perform well enough, as they slumped to a fourth successive Premier League defeat that leaves them 13th in the table, nine points clear of the relegation zone.
The 50-year-old, originally placed in caretaker charge when Alan Pardew departed for Crystal Palace in the new year, added: "It leaves a bitter taste in your mouth. A football club like ours shouldn't lose five in a row to our neighbours.
|Danny Murphy: 'More to Defoe than wonder goal'|
|I have never seen Defoe work as hard as he did to contribute defensively on Sunday - he tracked back on the left too and at one point he was making sliding tackles near his own corner flag, which was a first.|
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"I remember winning five in a row against them. The guys in the dressing room, along with us, have to do something about this.
"We have got 35 points and that might not be enough. There are seven games to go and we have to go and win some matches."