Substitute Gus finally floored Pompey after Harry Redknapp's men came back from 1-0, 2-1 and 3-2 with the winner two minutes from time.
It was the second 4-3 result at the Lane in four days and there was a reality check from the experienced midfielder.
"We have to improve," he stated. "You can't play every game at home and concede two, three or four goals. It's too much.
"Anyway, we were talking in the dressing room and to be fair, if you have to pick one of the games to win 4-3 and one to lose 4-3, we would have to say the Premiership, to get the points, to get better and improve.
"It was probably the youngest team in I don't know how many years, so that is positive news as well."
Gus Poyet wasn't too lost in the emotion of Saturday's 4-3 win against Portsmouth to admit: We have to improve.