Fernando Morientes' second-half brace against 10-man Boro guided Liverpool to a seventh successive Premiership win.
Mark Schwarzer's assured goalkeeping display and some inspired defending had frustrated Liverpool for 72 minutes.
But the visitors' defence was finally unlocked when Luis Garcia's cross was gathered by Morientes, who shot home.
Five minutes later, Morientes lobbed Schwarzer and Boro's misery was sealed by Chris Riggott's dismissal after he was booked for a second time.
Middlesbrough, ably marshalled by centre-backs Gareth Southgate and Riggott before he was sent off, defended superbly until Morientes broke the deadlock.
But the visitors' hopes of taking a point from the game were hindered by their inability to put the Liverpool defence under concerted pressure.
Another clean sheet for Reina means he has not conceded a Premiership goal for more than 10 hours, though in the closing stages he had a huge dose of luck in saving a James Morrison effort.
The result also ensured Liverpool equalled a club record of 10 straight clean sheets.
Liverpool made a barnstorming start, with Steven Gerrard alone having three shots on goal in the first five minutes.
The best of those three was a dipping effort well saved by Schwarzer after Gerrard had dispossessed Doriva.
The Boro goalkeeper's next job was to tip over a Morientes header after the Spaniard got above Franck Queudrue following John Arne Riise's long throw.
Five minutes before the interval, Schwarzer should have been beaten by Mohamed Sissoko.
Gerrard's diagonal pass was headed into the path of Sissoko by Crouch, but the former Valencia midfielder's header was straight at Schwarzer.
Soon after Liverpool passed up another good chance when Riggott's last-ditch tackle took the ball away from Crouch.
Amid this first-half Liverpool onslaught, Middlesbrough found it difficult to establish a line of communication to strikers Yakubu and Mark Viduka.
But within a minute of the restart that deficiency was rectified when Rochemback's deft first-time pass freed Viduka, who was left with just Reina to beat.
Although Reina was fooled by Viduka into diving the wrong way the Spanish keeper managed to clear with his feet.
Midway through the second-half Crouch was replaced by Garcia, a substitution that saw Gerrard move from the right of midfield into a more central position.
The change reaped an immediate reward when Gerrard and Garcia combined to set up Morientes for his first.
Garcia's cross skidded across the Boro goal to reach Morientes, who after bringing the ball under control, guided a shot into the corner of the net.
Boro almost immediately equalised when Viduka's pass released Morrison, whose shot was rather luckily saved by Reina.
Liverpool made the game safe after Morientes latched on to Queudrue's misguided header and he calmly lobbed the stranded Schwarzer.
Boro ended the game with 10 men when Riggott was red-carded after he collected a second booking for a lunge at Gerrard.
Liverpool boss Rafael Benitez:
"Fernando Morientes has been playing well but as a striker one of the most important things to score goals and he did that in this match.
"It is his best performance for Liverpool and he finished both his goals very well.
"The whole team performed well and it was a pleasing home display."
Middlesbrough boss Steve McClaren:
"I was disappointed with the red card for Chris Riggott and I felt Fernando Morientes was a couple of yards offside for their second.
"I have seen the second yellow for Chris and I have spoken to the referee, saying I felt there was no malice.
"It was a decision taken very quickly."
Liverpool: Reina, Finnan, Hyypia, Carragher, Riise, Gerrard,
Alonso, Sissoko, Kewell (Cisse 82), Morientes (Josemi 87),
Crouch (Luis Garcia 67).
Subs Not Used: Dudek, Warnock.
Goals: Morientes 72, 77.
Middlesbrough: Schwarzer, Bates, Southgate, Riggott, Queudrue,
Morrison (Hasselbaink 75), Doriva, Boateng, Rochemback, Viduka,
Yakubu (Ehiogu 86).
Subs Not Used: Pogatetz, Jones, Johnson.
Sent Off: Riggott (84).
Booked: Bates, Riggott.
Ref: S Bennett (Kent).