The Black Cats dominated the game, but lost 1-0 at home in the opening game of the new season.
"I was on a real high coming into the match after the hat-trick for the US team but walked off the pitch very disappointed at this result. we started positively, played good football but we let ourselves down with one stupid mistake and that cost us." Altidore told the Daily Mail.
"The coach didn't say too much, he was quiet. To play like that and come away with nothing is disappointing for us all. We'll take it upon ourselves to work on that and improve. I've already seen enough to know we've got a lot of talented players here and we'll be alright this season.
"The greatest thing about football is that there's always another game to quickly follow. We got done by a sucker punch and there's no other way of putting it, it really sucks.
"We'll go out onto the practice pitch, work hard and hopefully take our frustrations out on Southampton. There's no hiding the fact it was a bad result, but the team played positive football and if we play like that this season we'll be fine. You've got to take the positives from that."
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