Liverpool won a record-equalling penalty shootout 14-13 to progress to the fourth round of the Capital One Cup at Middlesbrough’s expense.
After the match ended 2-2, it took 30 penalties before Boro winger Albert Adomah missed to send the Reds through.
Liverpool had taken the lead through debutant Jordan Rossiter but Boro equalised when Adam Reach headed in.
In extra-time, Suso drilled home for the Reds but Patrick Bamford’s last-minute penalty forced a shootout.
Then came the real drama as the joint-highest scoring spot-kick contest in English professional football unfolded in front of a barely believing Kop.
Simon Mignolet saved Boro’s first penalty from Bamford only for Raheem Sterling to miss Liverpool’s fifth and send the shootout to sudden death.
Amazingly, the next 20 penalties were all scored as player after player from each side – including both goalkeepers – handled the pressure with aplomb, with several scoring twice.
But when Adomah pushed his kick wide, Liverpool could finally celebrate victory.
The result will relieve Liverpool boss Brendan Rodgers, whose side have lost three of their first five league matches and face Everton in the Merseyside derby on Saturday.
Boro, in contrast, will be devastated to have come so close to recording their first win at Anfield since 1976 after more than matching the Reds over 120 minutes of a pulsating cup tie.
With captain Steven Gerrard rested, 17-year-old academy product Rossiter was given his debut at the base of the Reds midfield, and he only took 10 minutes to make his mark.
After a long ball caused chaos in the Boro defence, debutant goalkeeper Jamal Blackman saved sharply from Rickie Lambert. But the ball fell kindly to Rossiter, who swept a low shot past Blackman’s flailing legs before wheeling away in delight.
Boro scored a deserved equaliser on the hour after Mamadou Sakho was penalised for handling a cross.
Grant Leadbitter’s free-kick from the right flank eluded the Liverpool defence and invited Reach to apply the headed finish from inside the six-yard box.
Rodgers introduced Mario Balotelli for the ineffective Lambert, but still Boro threatened.
And with five minutes remaining, Lee Tomlin’s superb reverse pass sent Clayton clear, but his strike cannoned off Mignolet’s near post.
In extra-time, Blackman saved long-range strikes from Jose Enrique and Sterling before substitute Suso put the Reds in front with his first Liverpool goal.
Adam Lallana and Enrique linked up well down the left and when Balotelli’s effort was only half cleared, the Spanish forward picked his spot from 12 yards.
But there was still time for another twist as Boro were awarded a penalty in the last-minute of extra-time.
After Sterling had given the ball away, Kolo Toure fouled Bamford, and the Boro substitute stepped up to beat Mignolet and take the tie to penalty kicks.