Cardiff City slumped to their first Championship loss of the year as Billy Davies' Nottingham Forest thrashed Huddersfield Town on Tuesday.
League leaders Cardiff suffered a 2-0 defeat to Brighton and Hove Albion, who had Andrea Orlandi and Leonardo Ulloa on the scoresheet in Wales.
It marked Cardiff's first loss in the league since December 15, 2012, but they remain five points clear at the top, while Brighton are seventh.
Davies' second game in charge in his second spell at Forest ended in a thumping 6-1 victory over Huddersfield at the City Ground.
Pole Radoslaw Majewski struck a first-half hat-trick and Elliott Ward also scored as the hosts took a 4-1 half-time lead following James Vaughan's 10th-minute opener for Huddersfield.
Henri Lansbury and Darius Henderson added to the scoring after the break as Forest ended a run of five matches without a win.
Elsewhere, Peterborough United continued their revival, extending Millwall's miserable run in the league with a 5-1 win.
A Lee Tomlin brace helped Peterborough extend their unbeaten run to four, moving off the bottom and within four points of safety as Millwall lost their fifth straight league outing.
The win saw Bristol City slip to the bottom after they suffered a 2-1 loss at fourth-placed Crystal Palace, who had leading Championship goalscorer Glenn Murray net again.
Hull City consolidated second spot with a 2-0 win over Blackburn, while Watford are third and recorded a 2-0 victory at Ipswich Town.
Leicester City were beaten 2-1 at home to Charlton Athletic but remain fifth despite their second straight loss.
Middlesbrough continue to cling onto the final playoff spot after playing out a scoreless draw at Burnley.
At Pride Park, Derby County came from behind to draw 1-1 against Bolton, while Birmingham City and Sheffield Wednesday drew 0-0.
Finally, Barnsley climbed out of the relegation zone with a 2-1 win over Wolverhampton Wanderers, coming from behind thanks to goals from Chris Dagnall and Jacob Mellis.