Newcastle captain Bruno Guimarães described his side's Tyne-Wear derby defeat to Sunderland as a "tough one to accept" and branded their performance "a mess."
The Magpies were beaten 1-0 at the Stadium of Light -- with Nick Woltemade's own goal settling the first league clash between the two rivals since 2016.
Defeat on Wearside leaves Newcastle 12th in the Premier League table and Guimaraes expressed his frustration after the game.
He said: "It's a tough one to accept for me. I'm very frustrated. One of those weeks we were very excited at the training ground, but we came here and didn't perform the way we can perform.
"So frustrated and it makes me feel angry about our performance today. We were not there. No shooting the ball, no crossing the ball, no passing. We should have demanded the ball more.
"I think we just accepted the way they will play, long balls, win the duels. In derbies we have to win the duels.
"It's so frustrating for me to come here today, but the fans are right [to criticise] because it's a tough one to accept.
"We had a great opportunity to go in front of them and we just missed it. For me it's so frustrating."
Following a first half of few clear-cut chances, Woltemade's inexplicable header in off the underside of his own crossbar gave Sunderland the advantage.
Guimaraes had Newcastle's first real chances after the hour mark, his two strikes saved by Robin Roefs, but the visitors struggled to test the Sunderland defence further.
Asked if this was his most painful defeat as a Newcastle player, Guimaraes added: "Definitely, yes.
"It's not just as a defeat, more the way we play.
"Disappointed, frustrated, lack of energy and no one put the things that we are able to do. Cross the ball, pass the ball, we're like a mess in my point of view.
"Disappointed, angry and this one is a tough one to accept."