By SABC Sport
20th December 2023
Mudryk slotted home after a mistake from Kieran Trippier just as Eddie Howe's side looked to have done enough to ease past the hosts, who struggled to create for much of the game.
Earlier, Callum Wilson had given the visitors a first-half lead on the counter-attack.
But as the game went to spot-kicks, Trippier again was culpable, firing wide from 12 yards before Matt Ritchie saw the critical kick saved by goalkeeper Djordje Petrovic to see Chelsea through.
The first chance went to the hosts. Enzo Fernandezs corner was flighted to the edge of the box where Conor Gallagher was waiting unmarked. Chelsea's captain took a touch and sent a crisp, arching shot over Martin Dubravka and against the face of the crossbar as Newcastle survived an early scare.
Chelsea were comfortably on top but then they gifted Newcastle the opening goal.
Levi Colwill, high in the opposition half, tried to find Moises Caicedo but horribly overhit his pass. From there, Wilson took over and drove over the halfway line.
He was marshalled by three defenders but Thiago Silvas challenge was weak, Benoit Badiashile stumbled over his own feet and Wilson had the simplest task of guiding it around Petrovic's dive.
Raheem Sterling twice came close to a quick response, first playing a neat one-two with Caicedo before rolling it wide of the far post, then smashing a shot goalwards from Cole Palmer's cut-back that was cleared off the line by Bruno Guimaraes.
Fernandez was withdrawn just past the half-hour mark, departing straight down the tunnel injured. Armando Broja was sent on up front, with Nicolas Jackson going to the left wing and Palmer moving centrally.
It made little difference, as possession in the middle third yielded little in the way of chances with Newcastle content to sit and wait for the chance to counter.
Jackson dragged an effort wide early in the second half then played in Sterling down the right who drew a good, low save from Dubravka as he shot towards the far corner. Chelsea, finally, were showing the kind of intent that might place pressure on Newcastle.
By the 65-minute mark the hosts were in total control of the ball, but the tempo of the game remained stubbornly gentle. The ball criss-crossed back and forth across midfield as Howe's defence simply drifted from left to right and back again, blocking any channels Chelsea hoped to exploit.
Gallagher dragged badly wide from the edge of the box before the moment home fans craved arrived with 20 minutes to play, Christopher Nkunku summoned from the bench to make a long-awaited debut after injury.
How misfiring Chelsea needed last season's Bundesliga top scorer, a £52million signing from RB Leipzig, to hit the ground running.
Instead it was another second-half substitute, Mudryk, who saved Pochettino, nicking the ball away from Trippier as he tried to head back to his goalkeeper.
A cool, curling finish sent the game to penalties and, after Petrovic's heroics from Ritchie's kick, put Chelsea on their way to the last four.