Alan Pardew's men continued their fantastic sequence of results with a home win over Steve Clarke's Baggies with a thumping volley sealing the points.
Yoan Gouffran opened the scoring with a close-range header following some suspect goalkeeper by Boaz Myhill but the Frenchman's effort was canceled out shortly after halftime by a rasping effort from Chris Brunt.
Moussa Sissokho went one better, though, firing in a right-footed half-volley from 25 yards that left Myhill with no chance of keeping it out as it flew into the top corner.
Newcastle made one change from the 2-1 win over Norwich, with Mathieu Debuchy returning from suspension and replacing Mapou Yanga-Mbiwa
The visitors brought Billy Jones, Liam Ridgewell and James Morrison into their starting XI, with Goran Popov and Claudio Yacob named among the substitutes and Steven Reid dropping out of the matchday squad.
Long was retained in attack after his brace in Monday's 2-2 draw against Aston Villa.
Chris Brunt's free kick tested Krul three minutes in, with the Dutchman forced to tip the ball wide, before Yohan Cabaye saw a long-range effort roll harmlessly wide of Myhill's post.
Newcastle grew into the game and saw Loic Remy's header deflected wide following good work on the right from Sissoko, while Shola Ameobi opted to shoot from distance rather than playing in his strike partner.
The pressure eventually paid off when Myhill could only parry a Cabaye corner skywards under pressure from Ameobi. Gouffran was on hand to convert from close range, scoring for a third consecutive home game.
Amoebi and Remy linked well early in the second half, the Frenchman denied by Myhill after being slipped in, but Brunt then equalized in emphatic fashion seven minutes after the break.
The West Brom captain registered his first Premier League goal of the season with a left-footed strike that crashed in off the underside of the crossbar.
Sissoko's thunderous strike three minutes before the hour swiftly put Newcastle back on top and Debuchy should have put his side 3-1 ahead 15 minutes from time but instead shot straight at Myhill from the edge of the area.
The wasted opportunity was not to matter as Newcastle held on to leave West Brom, which introduced Zoltan Gera late on for his first appearance since January, with just one win in its last seven matches.