Sunderland manager Dick Advocaat says his players were not up to scratch after losing 4-2 to Leicester City at the King Power Stadium on Saturday.
The Black Cats suffered a disastrous start to their league campaign when Jamie Vardy opened the scoring for Leicester before Riyad Mahrez hit a first-half brace and Marc Albrighton completed the scoring for the Foxes.
Jermain Defoe and Steven Fletcher each got a goal back in the second half, but it wasn't enough to undo the damage caused before the break.
"You can always lose if the other team is better, I can accept that, but the way we played in the first half was not good enough," Advocaat told Sky Sports.
"There was no sharpness and we didn't show that we wanted to win. Leicester wanted to win and we were always too late.
"I have seen what I already knew, it's difficult to change that at the moment but we have to change something because we cannot go on this way."
"In the first half, Leicester were sharper, better and deserved to win. We struggled to cope with their pace in midfield and at the back, so we have to think about what we need to do this week."