The 25-year-old Brazilian, a summer target for the Magpies, clinched a 1-1 draw with a 32nd-minute equaliser after Callum Wilson had ended his 10-game drought with an early strike.
A point was no more than the Hammers deserved after recovering from a dreadful start in front of a crowd of 52,256 to deny Eddie Howe victory in his 600th game as a manager.
The Carabao Cup finalists badly missed the suspended Bruno Guimaraes, and even the introduction of £45million January signing Anthony Gordon for his debut could not get them over the line.
Howe, who confirmed record signing Alexander Isak had sat out under concussion protocols, said: "Because of our form this season, these types of games feel like defeats. When you're in my shoes, it's important to see the bigger perspective and see other things.
"I have to make sure the players don't overreact to what is a point. People might say it's a disappointment, but it depends on what context you're looking at it in. You can see four draws in five, or you can see 16 games unbeaten.
"I like to be very realistic and look at objectively and not rose-tint it, but I can't criticise the players for what they've delivered this week or what they've delivered today."
Howe handed a debut to £45million January signing Anthony Gordon as a second-half substitute and was happy with what he saw from the 21-year-old.
He said: "I was very pleased with him. Your first action here at St James' Park is important. His first pass was a brilliant one and he injected some life into us at a time when we needed it in the game.
"I'm disappointed for him that we couldn't get him in the box and see what he can do closer to goal, but he did really well when he came on."