Dick Advocaat has admitted that he is at a loss to explain his Sunderland side's performance after they were beaten 3-1 at home by Norwich City on Saturday.
Duncan Watmore scored a late consolation for the Black Cats at the Stadium of Light, and while Advocaat refused to criticise his players, the Dutchman was unable to analyse where his team went wrong.
Advocaat told Sky Sports News: "It was not so easy to explain. I cannot complain about [the effort] they gave everything.
"But when the players started playing, I cannot explain. We will try to find out what it was and we will speak tomorrow. It was even worse than last week. We have to do it simple and if we can't do it simple, we have a problem."
Advocaat also admitted that he could understand why thousands of supporters decided to leave stadium long before the final whistle.
"I can understand that," he added. "The expectation was high after last season, and we have to do better than last year but we have started the same."
Sunderland host Swansea City next week.
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