Newcastle United legend Alan Shearer has unleashed a scathing critique of the Magpies following their demoralising 2-1 defeat to arch-rivals Sunderland. The Premier League's all-time record goalscorer did not hold back after witnessing a second-half collapse that saw Eddie Howe's side surrender a 1-0 lead at St James' Park as the Black Cats celebrated another win over their bitter rivals.The atmosphere at St James' Park turned toxic on Sunday as Newcastle United failed to capitalise on a strong start, eventually falling to a 2-1 defeat against rivals Sunderland. While the Magpies took an early lead through Anthony Gordon, their performance levels plummeted after the interval, prompting a furious response from the club great.Taking to social media to voice his frustrations, Alan Shearer delivered a damning 10-word verdict: "A pathetic, weak, lazy, limp second half from Newcastle again #NEWSUN."Newcastle had initially looked totally in control of the contest. Gordon found the back of the net in the 10th minute, and for the remainder of the first half, Sunderland struggled to register any meaningful threat. However, the second period told a completely different story as Regis Le Bris’ side emerged with renewed intensity.The Black Cats' dominance was eventually rewarded in the 57th minute when Chemsdine Talbi tapped home from close range.The match was not without its share of controversy, particularly when Malick Thiaw thought he had restored Newcastle's lead with a powerful header. Referee Anthony Taylor consulted with his officials and ultimately disallowed the goal, ruling that Jacob Murphy was in an offside position and successfully blocking the vision of goalkeeper Melker Ellborg.Sunderland took full advantage of that reprieve in the final moments of the match. Brian Brobbey secured a famous victory in the 90th minute, firing home after his initial effort was saved to spark wild celebrations in the away end.The result means Sunderland have completed a league double over their fiercest rivals, moving above them into 11th place in the Premier League table.Add GOAL.com as a preferred source on Google to see more of our reportingFormer Liverpool defender Jamie Carragher was also on hand to provide analysis, noting the historical significance of the result. Speaking to Sky Sports, he highlighted how long it had been since the Black Cats had tasted such success on enemy territory. "[It is] 10 years since they have played at St James' Park in the Premier League, and Newcastle just cannot beat Sunderland," Carragher observed.He continued: "What a moment for them, probably never dreamed in these last four or five years that they could beat Newcastle. Got up surprising through the play-offs last season, and to do the double over their biggest rivals, one of the best moments their young fans will remember."