A place in the semi-finals and a step nearer the UEFA Cup next season is at stake when Wanderers arrive at the Lane for the second time in eight days tomorrow night.
And Gus, who scored in last week's thrilling 3-2 Premiership win against Sam Allardyce's men, is determined to book our place in the last four of the competition.
"I always say in cups, the great point is the semi-final," said the in-form Uruguayan. "In the semi-final you realise you are almost there, one or two steps from Europe. So this is the game to win.
"After that it's different because when you play a semi-final it is like a final anyway.
"This is probably the most important game of the season.
"If you look at how many games we have to play to finish sixth in the Premiership, another 22, but here we have three games, three games away from Europe. It is a great chance and everyone knows that."
Meanwhile, Gus insisted his late volley in Saturday's 3-1 defeat at Charlton - his seventh goal in nine games - felt like it 'didn't count'.
"It's like it doesn't count," he said. "It will be there at the end of the season when you add up the goals but it's a goal you don't like to score because it doesn't make you win.
"Yes, it's nice to keep scoring and you keep a good level in front of goal but apart from that it was disappointing. We lost a great chance to move up in the table.
"Anyway, after two or three days we are back on the pitch. It's different competition but a chance to get into Europe so we need everyone fit and every supporter in the stadium behind the team."
Gus Poyet has labelled Tuesday's Worthington Cup clash against Bolton as the most important game of the season so far.