Newcastle's Championship title hopes were dealt a blow as Nottingham Forest claimed a fourth straight win.
Dexter Blackstock struck on the stroke of half-time to reward a dominant first-half performance by Forest and knock the Magpies off their perch.
The visitors were much improved in the second half but Forest held on to go joint fifth on 21 points, within just five points of the top of the table.
West Brom are the new leaders having crept above Newcastle earlier in the day and a third game without a win for the Magpies means they remain behind the Baggies on goals scored.
Disallowed goalNewcastle had a Kevin Nolan goal disallowed midway through the second half but otherwise they struggled to create chances.
In-form Forest, by contrast, came out flying from the first whistle and Newcastle goalkeeper Steve Harper adjusted quickly to claw away Blackstock's third-minute header before keeping out Radoslaw Majewski's curling effort.
The home side continued to dominate and went agonisingly close to taking the lead in the 13th minute when Majewski's corner was headed against a post by Blackstock, who lost his marker Zurab Khizanishvili.
Newcastle almost went ahead against the run of play when Ryan Taylor delivered a teasing free-kick and former Forest striker Marlon Harewood glanced the ball against a post from six yards.
Andy Carroll fired wide and Harewood headed over, but the Magpies laboured in front of goal while Forest were doing everything but score at the other end.
Paul Anderson was denied by Harper and sent another opportunity wide, with Nathan Tyson and Blackstock also missing the target.
Deserved openerBut the goal Forest deserved came in the 45th minute when Majewski played a through-ball which split the Newcastle defence and Blackstock beat the offside steer to lift the ball wide of Harper and inside the far post.
Newcastle upped their game after the break, beginning with Peter Lovenkrands blazing over after being teed up by Kevin Nolan.
Harewood, desperate for a goal on his return to the City Ground, then turned sharply in the area but was denied by a fine block from Kelvin Wilson.
The visitors were denied an equaliser in the 69th minute when Taylor's cross was flicked on by Alan Smith into the path of Nolan.
The former Bolton midfielder poked home at the far post but his celebrations were cut short by an offside flag.
Toon boss Chris Hughton threw on substitute Nile Ranger but the youngster blew his only chance to earn his side a point when he headed over from a corner.