Fabricio Coloccini fears the Toon face a relegation battle if they don't learn from simple mistakes.
The Magpies suffered a shock 3-2 defeat at home to Hull City on Saturday afternoon - having twice led through goals from French striker Loic Remy.
Coloccini feels it was a great opportunity to climb up the table by winning three games on the bounce.
The Argentinian defender told the Shields Gazette: "There were bad feelings – frustration, anger, and everything you’d expect.
"It’s difficult to speak about it because a lot of things happened on the pitch that I’m angry about.
"We had a great, great chance to take three more points at home against a newly-promoted team.
"It was a great opportunity. If we want to be serious about being in the top 10, or look to bigger things in the Premier League, we have to start to take the chances we have.
“If not, we’re going to have problems. We do not want to be like we were last season. We ended the season fighting against relegation, and we can’t have that again.
"When we have chances to beat teams like Hull, we have to take them."
Goals from Robbie Brady, Ahmed Elmohamady and Sone Aluko meant Steve Bruce was the only Geordie leaving St James' Park with a smile on his face.
Toon boss Alan Pardew claimed his side has taken their foot off the gas and looked "loose" in a number of areas.
"I can’t say it is day I will fondly remember. I was standing on the sidelines and disappointed with a lot of factors about the game.
"The thing we must improve on is our consistency of performance as individuals and as a team. This is a place where we need to crank it up all the time and keep the pressure on."
Newcastle owner Mike Ashley watched the game from the stands alongside his director of football Joe Kinnear.
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