Lee Johnson felt Bolton Wanderers' fifth and sixth goals in the rout against his Sunderland side underlined a 'soft underbelly' that the Black Cats have.
Dion Charles put Wanderers ahead before Dapo Afolayan added a second before half-time.
Charles bagged his second after the break before Kieran Lee added a fourth as Wanderers blitzed the Black Cats.
READ MORE: Bolton Wanderers player ratings as Dion Charles and Dapo Afolayan brilliant in Sunderland rout
Danny Batth put through his own net to add a fifth for the hosts before Declan John rounded off the win with a sublime sixth goal as a rampant Wanderers made it three victories on the bounce.
The defeat left Johnson having to apologise for the loss to the club's supporters, and he felt the fifth and sixth goals conceded showed a 'soft underbelly' his side has.
And he admits he did not see the huge defeat coming after preparing well for the encounter at the University of Bolton Stadium.
He told our colleagues at ChronicleLive: "It was [a soft underbelly] today.
"We've had some great away wins but today I can't argue.
"The fifth and sixth goals ... it did look like we have a soft underbelly.
"It's up to me to call out some home truths.
"I still believe in my players: that hasn't changed.
"I have to take responsibility for that game today. I don't want to, if I'm honest, because it hurts to do that, but I have to because part of my job is to get the boys tactically right but also to get them mentally right and focused and despite believing I and my staff did that, we clearly didn't show it so that's on me.
"We go back to drawing board with the players on an individual and on a collective basis.
"I felt we prepared well for the game, the pitch was good, but we played into their hands very early and we have to accept that their gameplan was extremely well executed right from the first action when we switched the play and Carl Winchester should have spun the ball in behind but he turned back.
"We were prancing, we looked posey, and it played into their aggressive pressing game.
"Both teams in the first 20 minutes didn't really get too much play going and it was a tale of two goalkeepers kicking the ball out of play, which was very frustrating.
"We do work during the week and I did say to the players that it's all very well having a great week, but you have to bring out your best when it matters most - and when it matters most is on a Saturday.
"We have fallen unbelievably short today in every facet of football.
"It's a big shock to me this performance.
"I genuinely didn't see it coming.
"I can only hold my hands up and accept responsibility for it."
