Fernando Torres piled more agony on Middlesbrough as his splendid hat-trick won this game for Liverpool, adding to the stunning 30-yard effort that claimed a point at the Riverside last month for Rafael Benitez's side.
The Spaniard has become the first Liverpool forward to hit 20 goals in a season for five years, his total now being 21 since his £20million move to Merseyside.
But Liverpool were made to fight for the win that takes them back into fourth spot.
Tuncay Sanli's header gave Boro an early lead before Torres struck twice in two minutes before the break.
He completed his hat-trick, the second since he arrived at the club, on the hour.
But Stewart Downing kept his side in the game with a goal in the closing minutes.
However any chance Middlesbrough had of grabbing a point was ruined when Jeremie Aliadiere was sent off after an incident with Javier Mascherano.
Liverpool decided on Alvaro Arbeloa as the stand-in for the suspended Jamie Carragher. Martin Skrtel was only considered fit enough for the bench after an ankle problem.
A ninth minute free-kick from Downing curled into the box for Tuncay to head home, to the dismay of a static Liverpool defence who assumed he was offside. Mascherano's positioning on the back post disproved that theory.
Liverpool's response was scrappy, to say the least. The closest they came was when Dirk Kuyt fired over after a Ryan Babel run and cross.
From a side who had outshone Inter Milan in midweek, Liverpool had reverted to their former self.
Passes were going hopelessly astray, with possession constantly conceded and not a hint of rhythm.
It took Torres to pull Liverpool together. Jose Reina's clearance on 28 minutes was headed by Julio Arca straight to the Spaniard.
He raced away, went round Mark Schwarzer and then found the net with his right foot.
Sixty seconds later Torres struck again. Fabio Aurelio found the striker in midfield and Torres lashed home a 25-yard shot into the bottom corner.
Aliadiere was booked for a foul on Aurelio, before Tuncay thought he had equalised, sending a Downing cross past Reina on 34 minutes.
But referee Lee Mason ruled the Boro man had used his arm and booked the forward.
Boro were still in the game and put Liverpool under pressure early in the second period.
On 53 minutes Reina and David Wheater were booked after an incident at a corner. The Boro defender looked to have flicked his heel at the keeper, who reacted angrily.
Six minutes later Boro sent on an extra striker in Mido, replacing Gary O'Neil.
Liverpool, without Carragher, had not looked comfortable in defence all afternoon.
But again Torres bailed them out when he completed his second hat-trick for the club, the first being at Reading in the Carling Cup in September.
On 60 minutes, Kuyt's hard graft in defence saw him win the ball and launch a 50-yard angled ball towards the Spanish striker.
It looked like Wheater would comfortably tidy up the situation, but with Schwarzer almost alongside him now, there was hesitation between the pair and Torres took advantage to hook the ball home from the edge of the box into an empty net.
Yossi Benayoun came on for Babel before the restart, and Fabio Rochemback was booked for a foul on Torres.
Torres was on a roll by now and took a Steven Gerrard pass before outpacing Emanuel Pogatetz and forcing Schwarzer into a good save to his right.
John Arne Riise came on form Kuyt on 73 minutes, the hard-working Dutchman getting a well-deserved ovation from all sides of the ground.
Middlesbrough got themselves a lifeline on 83 minutes when Downing got in behind Benayoun on the left to run on into the box before beating Reina from a sharp angle.
But three minutes later Aliadiere was sent as he slapped Mascherano after an exchange between the pair on the touchline.
The Liverpool man seemed to have patted the French youngster on the cheek a second earlier.
Two minutes from time Luke Young was booked for tripping Mascherano from behind.
The Spaniard has become the first Liverpool forward to hit 20 goals in a season for five years, his total now being 21 since his £20million move to Merseyside.
But Liverpool were made to fight for the win that takes them back into fourth spot.
Tuncay Sanli's header gave Boro an early lead before Torres struck twice in two minutes before the break.
He completed his hat-trick, the second since he arrived at the club, on the hour.
But Stewart Downing kept his side in the game with a goal in the closing minutes.
However any chance Middlesbrough had of grabbing a point was ruined when Jeremie Aliadiere was sent off after an incident with Javier Mascherano.
Liverpool decided on Alvaro Arbeloa as the stand-in for the suspended Jamie Carragher. Martin Skrtel was only considered fit enough for the bench after an ankle problem.
A ninth minute free-kick from Downing curled into the box for Tuncay to head home, to the dismay of a static Liverpool defence who assumed he was offside. Mascherano's positioning on the back post disproved that theory.
Liverpool's response was scrappy, to say the least. The closest they came was when Dirk Kuyt fired over after a Ryan Babel run and cross.
From a side who had outshone Inter Milan in midweek, Liverpool had reverted to their former self.
Passes were going hopelessly astray, with possession constantly conceded and not a hint of rhythm.
It took Torres to pull Liverpool together. Jose Reina's clearance on 28 minutes was headed by Julio Arca straight to the Spaniard.
He raced away, went round Mark Schwarzer and then found the net with his right foot.
Sixty seconds later Torres struck again. Fabio Aurelio found the striker in midfield and Torres lashed home a 25-yard shot into the bottom corner.
Aliadiere was booked for a foul on Aurelio, before Tuncay thought he had equalised, sending a Downing cross past Reina on 34 minutes.
But referee Lee Mason ruled the Boro man had used his arm and booked the forward.
Boro were still in the game and put Liverpool under pressure early in the second period.
On 53 minutes Reina and David Wheater were booked after an incident at a corner. The Boro defender looked to have flicked his heel at the keeper, who reacted angrily.
Six minutes later Boro sent on an extra striker in Mido, replacing Gary O'Neil.
Liverpool, without Carragher, had not looked comfortable in defence all afternoon.
But again Torres bailed them out when he completed his second hat-trick for the club, the first being at Reading in the Carling Cup in September.
On 60 minutes, Kuyt's hard graft in defence saw him win the ball and launch a 50-yard angled ball towards the Spanish striker.
It looked like Wheater would comfortably tidy up the situation, but with Schwarzer almost alongside him now, there was hesitation between the pair and Torres took advantage to hook the ball home from the edge of the box into an empty net.
Yossi Benayoun came on for Babel before the restart, and Fabio Rochemback was booked for a foul on Torres.
Torres was on a roll by now and took a Steven Gerrard pass before outpacing Emanuel Pogatetz and forcing Schwarzer into a good save to his right.
John Arne Riise came on form Kuyt on 73 minutes, the hard-working Dutchman getting a well-deserved ovation from all sides of the ground.
Middlesbrough got themselves a lifeline on 83 minutes when Downing got in behind Benayoun on the left to run on into the box before beating Reina from a sharp angle.
But three minutes later Aliadiere was sent as he slapped Mascherano after an exchange between the pair on the touchline.
The Liverpool man seemed to have patted the French youngster on the cheek a second earlier.
Two minutes from time Luke Young was booked for tripping Mascherano from behind.