The Uruguayan suggested that several of his players gave up in the second half, and the Black Cats boss was far from pleased with what he saw at St Mary's as they slipped to a humiliating Premier League loss.
"Well first, it was embarrassing, I think it is probably the most embarrassing time I've had on a football pitch," he told Sky Sports News. "You think that you will never be in this situation but unfortunately it is your turn and I said that I am really sorry for the fans, as they have travelled a long way and they have seen a very difficult game today.
"[What I said to the players] is in inside the dressing room and it is for ourselves. We conceded an own goal that is unique, it is not the usual own goal. I know it is 8-0 and I won't use this as an excuse, but we should have had a penalty and their goalkeeper could have been sent off.
"The only thing you want is not to throw the game away [at 3-0]. We know that it is enough but I learned a lot about my players today. The characters, the ones who stopped and the ones who give up and I know who they are. It is very important for me for the future."
Sunderland's biggest ever top-flight defeat leaves them 17th in the Premier League table.