Newcastle cruised to a 4-0 win on Saturday to ease some pressure on the players and manager Eddie Howe.
Guimaraes later said, "I think we stepped up in this game. It was a massive win. The team played well, especially in the second half.
"I am very happy to score again. I have been trying for a long, long time, but I wasn't lucky. But very happy for today and we need to keep going. We have a massive game on Wednesday.
"Our message in the changing room during half-time was to try to score the second goal as quick as possible for the confidence, I think we deserved to win the game and played much better than against Brentford.
"We need to step up in all games and not just against the big six. Today was a big proof that this team can do big things together."