Newcastle head coach Steve McClaren admits his side "wasted" a game in their battle to avoid relegation after a 3-0 defeat at Everton.
Two late Ross Barkley penalties, the second of which saw substitute Jamaal Lascelles sent off, followed a first-half Aaron Lennon strike as the Toffees recorded their first home league win since November.
Defeat, which also saw the Magpies lose defenders Chancel Mbemba and Paul Dummett and midfielder Henri Saivet to injuries inside 55 minutes, left Newcastle two points from safety.
McClaren said he had spoken to his players about making the most of every one of their remaining fixtures but felt they had thrown this one away.
"We have said you can't waste a game now and that's what we've done," he said.
"We felt we could come here and get a result but we had to come here and perform at our level and there were a lot of players below that level and that is why we lost.
"Some of them know they have fallen short. That is not what we have come to expect and you can't afford to do that with games ebbing away.
"A few players who did not play at the level and didn't show their quality which is why we lost.
"In terms of injuries and performance that is not our level of performance which we have been producing."
The nature with which they conceded two penalties in the last two minutes raised questions about the players' attitude but McClaren insisted there was nothing wrong in that department.
"The attitude has been a different class the last couple of months," he said.
"We had bad results against Leicester and Crystal Palace (in November) where that (attitude) was questioned but since then it has been excellent.
"I felt it was disappointing we returned to that level and that is unacceptable."
Everton boss Roberto Martinez marked his 100th Premier League match in charge at Goodison with his 40th win - and only a second home clean sheet of the season.
Having led 1-0 for so long he was pleased with the way his side closed out victory having shipped costly late goals on several occasions recently.
"I thought it was the first time this season we managed the game for 90 minutes," he said.
"The big difference from our other home games was when the opposition had a good spell the ball ended up in the back of our net but [tonight] we probably anticipated that and defended with a real intensity.
"I thought it was a real professional performance. In the second half, when you expected Newcastle to have a bit of a reaction, we had two or three opportunities and scoring that second goal [earlier] would have been very different but we didn't let that affect the scoreline."
Barkley was at the heart of Everton's best moves and Martinez paid tribute to the England midfielder on his 100th Premier League appearance.
"Probably last year and the season before he was a young man with enormous potential, today he showed he is not a young man any more in footballing terms," he added.
"He is a player who is ready to lead the team; his decision-making has gone to a different level and I don't think he is a potential player any more."
Everton lost leading scorer Romelu Lukaku to a back injury at half-time and the striker is a doubt for Saturday's trip to Stoke while defender John Stones missed the game with a hamstring problem and will be out a little longer.
"He (Lukaku) couldn't walk. He had a knee in his back and tried to run it off in the first half and couldn't," said Martinez.
"We are playing on Saturday and it will be difficult to see him make it but it is not a major problem.
"Stones had a bit of a niggle in his hamstring and he had a scan yesterday and it was all clear.
"I think it was a fatigue reaction. He is 21 and at this stage has played more games than at any time in his professional career.
"I expect him to be back in the next week or 10 days."