Newcastle won 2-0 thanks to goals from the Brazilian and Nick Woltemade.
“It was a huge win for us,” Howe said. “We’ve done really well to recover from the Arsenal game and refocus on two really important matches. It was vital we won today.
“We played some really good football in both halves against tough opponents. The group are always so professional and hungry to win.
“He’s (Guimaraes) capable of that and he’s a goal threat when we get him higher up the pitch. It was a brilliant long range finish.
“He’s been such a dependable player and been such a leader for us in terms of standards and quality.”
On Woltemade, Howe added: “I thought he showed real composure and confidence and that’s a great sign for him.
“He’s made such a positive impression around the training ground and also delivered on the pitch. I think today was arguably his best game, so I’m really pleased for him.”