It took extra-time to resolve the issue along with a couple of master-class substitutions from Jose Mourinho when he sent on Eidur Gudjohnsen and flying Dutchman Arjen Robben.
The deadly duo pounced for both of the goals, one in each period of added time, to fire Chelsea into the quarter-finals and a derby clash against Fulham at Craven Cottage.
Gudjohnsen had only been on the pitch for 181 seconds when he finished superbly, drilling the ball beyond Shay Given to make it six goals in his last half-dozen games for Chelsea against Newcastle.
The Icelandic international said: "The manager said it would depend on how the game developed if I was to go on and he made the right decision."
As regards to his regular goals bonanza against Newcastle, Gudjohnsen added: "I don't know why I do so well against them. It's a nice stadium and I like playing against them."
The pace and direct running of Robben caused countless problems when he was introduced after 63 minutes and his strike to settle the issue was out of the top drawer.
He intercepted a Wayne Bridge pass down the left and ghosted past Andy O'Brien and Titus Bramble before executing the most perfect of finishes to see Chelsea through and leave Newcastle totally deflated.
O'Brien, with Sunday's blunder still fresh in his memory, almost gift-wrapped Chelsea a second minute lead.
In fact, just 73 seconds had gone when Mateja Kezman intercepted O'Brien's weak back-pass. However, he was forced wide by Given and fired left-footed across the face of the unguarded goal.
It was a difficult start for United who found Chelsea's passing game difficult to handle.
Gradually Newcastle found their feet and composure and Laurent Robert tested the recalled Carlo Cudicini.
Ronny Johnsen just failed to control a Robert free-kick and the ball drifted wide as United upped the tempo and Cudicini was then forced to hold onto a shot from the disappointing Patrick Kluivert.
Glen Johnson then wasted a good chance when he broke on the right following the deftest of flicks from Joe Cole but, with numbers in support, disappointingly fired wide.
Cudicini then kept out Olivier Bernard's effort with an excellent fingertip save just before the break. Clever work from Robert released his fellow Frenchman whose low drive, destined for the corner, was deflected narrowly wide by the keeper.
With Nicky Butt having already been cautioned and spoken too a further couple of times by referee Steve Bennett, it was no surprise when Kieron Dyer replaced his England team-mate at the break. The last thing Souness wanted was Butt red-carded and forced to miss Sunday's clash with former club Manchester United.
Bramble may well have forced his way into contention for that game following an imperious display in the heart of the defence.
Tiago should have forced Chelsea in front after 65 minutes when he was played in by Kezman, rounded Given and then inexplicable poked the ball wide.
Bramble had a header scrambled away as United pushed for victory.