The in-form Adam Johnson made it 2-0 within four minutes after Krul could only parry Jack Colback's deflected effort, his seventh goal in as many games, and Colback made sure 10 minutes from time with the Magpies in disarray.
Poyet said: "What a league this is. We need to keep going.
"Before I said we needed to get safe somehow; now if we don't stay up, it would be a shame because we have done a terrific job until now.
"Now we are in a position where it is in our hands and we need to take it, so I am going to make sure that we do the right things from now until the end of the season."
On debutant Liam Bridcutt, Poyet added: "He knows the role perfectly. If there is one person in the world who knows the role I want that player to play, it's Liam.
"Not being able to play Lee Cattermole because he was injured for the last couple of games, it was a relief for me to have Liam in the team.
"I had no doubt about playing him and giving him a debut because I know that he knows what I want and what is needed in that role."