With 52 minutes on the clock, Gus received the ball from Darren Anderton in the penalty area and applied a sweet finish and it is to be imagined that all in the ground, bar one, thought we were one goal to the good.
It was not to be as the assistant referee held his flag aloft and referee David Elleray chalked off the goal.
Video evidence showed clearly that Gus was not offside and he feels that had the goal stood we would have won the game.
"Looking at it on the video I am onside so it is even worse now," said Gus. "Often with this kind of game, if you score first you win it.
"It was tight, it was difficult, it was competitive - so it was always likely to be a case of who scores first.
"I got the chance. I didn't know when I got the ball, I just went in there to try and score. I started celebrating then saw that flag up.
"I didn't know whether I was offside or not at that time really - you cannot complain when you are not sure. I have seen it in the dressing room now though."
Just a couple of minutes after half-time Gus was also in the thick of the action, pouncing on a poor clearance from Newcastle keeper Shay Given and attempted to send the ball back over his head.
The Irish international recovered enough ground to just tip Gus's accurate effort over the bar.
"That was a good save, I really hit it well because it was spinning. I was not in the best position but I did hit it well. It was a really good save.
"That was something special. You never expect to score a goal like that - but the other one makes me feel sad."
Viewing a replay of his goal that wasn't did not improve the mood of Gus Poyet after the late defeat to Newcastle.