An absolutely dire performance from the Reds sees them slip down to third after Chelsea dramatically beat Wigan 2-1 at Stamford Bridge. Rafa Benitez’s men are now seven points behind United, who have played a game less.
Captain Steven Gerrard returned to action following a hamstring injury for the visit to the Riverside Stadium.
And youngster Nabil El Zhar made his full league debut having made many sub appearances this season and previously only started in the League Cup.
Also coming into the team were Sami Hyypia – who replaced the injured Alvaro Arbeloa, with Skrtel switching to right back – and Ryan Babel on the left of midfield.
Liverpool started brighter and had good chances through El Zhar and Kuyt.
Middlesbrough, who hadn’t won a league game since early November, got some luck just after the half an hour mark when Stuart Downing’s corner fell onto the leg of Xabi Alonso and deflected in past a despairing Pepe Reina to give the hosts the lead.
The Reds never really looked like equalising and were punished for their lacklustre attitude to the match when Boro struck again to double their lead just after the hour mark.
A swift counter-attack down the right caught the Liverpool defence off-guard and Tuncay found himself in plenty of space inside the box and duly slotted home.
Gerrard and Carragher, both looking tired or off the pace, were replaced by Benayoun and David N’gog but the Reds lacked inspiration and looked to be feeling the effects of their midweek heroics in Madrid.
Middlesbrough: Jones, Hoyte, Wheater, Huth, Pogatetz, O’Neil, Bates, Arca (Walker 88), Downing, Sanli (Adam Johnson 79), Aliadiere (King 68).
Subs Not Used: Turnbull, Taylor, Emnes, Alves.
Booked: Sanli, Bates.
Goals: Alonso 32 og, Sanli 63.
Liverpool: Reina, Carragher (Benayoun 71), Hyypia, Skrtel, Aurelio, Alonso, Mascherano, Kuyt, Gerrard (Lucas 76), Babel, El Zhar (Ngog 68).
Subs Not Used: Cavalieri, Dossena, Riera, Darby.
Referee: Rob Styles (Hampshire)
Next Up: Sunderland (h) Tuesday, 8pm