Liverpool's fading Premier League title hopes suffered a crushing blow as they lost 2-0 to strugglers Middlesbrough at the Riverside.
A Xabi Alonso own-goal and a Tuncay Sanli effort - one in each half - did the damage, while the visitors missed a host of chances in the absence of injured striker Fernando Torres.
Liverpool remain seven points behind leaders Manchester United, who play the Carling Cup final on Sunday, after suffering just their second defeat of the current campaign. They drop to third behind Chelsea.
Captain Steven Gerrard went off a quarter of an hour from the end, as Rafa Benitez's side failed to conjure one of their trademark late surges.
Liverpool's title challenge might have been over long ago were it not for their amazing penchant for comeback victories.
They set the tone for a season of last-gasp heroics in their opening home game back in August, when Boro led until the 86th minute before an Emanuel Pogatetz own-goal and a 94th-minute Gerrard stunner turned the game around.
So Boro's opener against the run of play ought not to have disheartened the visitors unduly.
However, Liverpool heads visibly dropped at a classic sucker punch just after the half-hour mark. Stewart Downing swung his corner in from the right and Alonso, who appeared to be having his shirt pulled, inadvertently redirected the ball past Pepe Reina and into the far corner off his left hip.
Middlesbrough led despite failing to record a serious goal attempt - their only effort a sliding Gary O'Neil shot straight at Reina from close range.
Liverpool, despite the absence of Torres, had created plenty of openings and ought to have been in front by then.
Dirk Kuyt, Ryan Babel and the young Moroccan Nabil El Zhar operated as a fluid front three, switching positions and causing problems with their movement.
Kuyt had the game's first shot with a low effort from the right side of the box that Brad Jones parried, and his follow-up was blocked.
The Dutchman had an even better chance shortly afterwards when a left-wing cross from the impressive Fabio Aurelio was deflected into his path. He had time and space 10 yards out, but Jones managed to help his high, hard shot over the bar.
Babel and Gerrard also went close - the returning captain looking odds-on to score but was denied by a brilliant David Wheater block.
The second-half started in similar fashion, with Liverpool creating plenty of chances but failing to finish them.
El Zhar, generally useful despite his surprise selection ahead of Yossi Benayoun, had a golden chance when Gerrard pulled the ball back from the left, but the young Moroccan side-footed the ball hopelessly over.
Sixty-two minutes in, Tuncay made it two as Boro executed a superb counter-attack. O'Neil released Jeremie Aliadiere down the right and the Frenchman laid on a simple pass for Tuncay to finish inside the left-hand post.
Benitez's strikers could only wonder what might have been if they had finished so clinically, and the introduction of David Ngog only reinforced their lack of options. Robbie Keane may not have been perfect, but he was a sight better than this.
Kuyt suffered more indignity on 68 minutes when Gerrard surged into the box and crossed low to the unmarked striker, who somehow failed to make contact with the ball in front of an open goal.
When Gerrard - still not fully fit after his hamstring injury - went off 15 minutes from time, the game was effectively up for Liverpool.
On Friday the Reds lost their chief executive Rick Parry - 24 hours later they may well have seen their title hopes depart.