The two sides played out a goalless draw at Villa Park, although the Italian should have put the Black Cats ahead just before half time but somehow managed to fire over the bar from two yards out.
Poyet revealed that the 28-year-old forward, who arrived from Juventus in the summer, has since apologised to his teammates.
"He's so sad," the Uruguayan told reporters. "He doesn't stop thinking about it and saying sorry, but that's football and things happen for a reason sometimes."
He added: "For us it was our best performance away from home because we made it difficult for them.
"We were brave on the ball, we created two or three very good chances so for a team down at the bottom playing away from home I don't think it's too bad."
The Mackems are 19th in the Premier League, five points from safety.