Newcastle moved within touching distance of the League Cup final as Joelinton clinched a 1-0 win against Southampton in Tuesday's semi-final first leg.
Joelinton netted in the second half at St Mary's to put Eddie Howe's side on the brink of their first domestic cup final since 1999.
Southampton's Duje Caleta-Car was sent off in the closing stages as a feisty clash boiled over.
Nathan Jones' team, bottom of the Premier League, felt hard done by after Adam Armstrong's equaliser was disallowed by VAR for handball.
But Newcastle can book their long-awaited trip to Wembley in the second leg at St James' Park on January 31, with the winner facing Manchester United or Nottingham Forest in the final.
Forest host United in the first leg of their semi-final on Wednesday.
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Newcastle are enjoying a renaissance this season thanks to Howe's astute leadership and the financial investment of the club's Saudi-backed ownership group.
The Magpies sit third in the Premier League and are making their first domestic semi-final appearance since 2005.
Underlining Newcastle's new, confident attitude, Howe had said merely reaching a semi-final was "not enough" as he aims to win the club's first major domestic trophy since the 1955 FA Cup.
The Magpies' most recent domestic cup final ended in defeat against Manchester United in the 1999 FA Cup, with their last major silverware coming in the 1969 Inter-Cities Fairs Cup.
For Newcastle, this is their most promising period since the Kevin Keegan era in the 1990s and they left the south-coast having taken another step on the road back to relevance.
Joe Willock should have put Newcastle ahead inside two minutes when he fired wildly over after Miguel Almiron's pass found the unmarked midfielder in the Southampton penalty area.
Willock fluffed his lines again with a wayward volley after Kieran Trippier's pin-point cross picked him out at the far post.
When Willock finally got a shot on target, Saints keeper Gavin Bazunu made the save, with Joelinton's close-range finish from the rebound disallowed for handball.
Carlos Alcaraz was making his first Southampton start since signing from Racing Club and the midfielder forced a save from Nick Pope with a long-range strike.
Teed up by Almiron's raid down the left flank, Sean Longstaff blazed over from the edge of the area early in the second half.
Joelinton fared even worse when Almiron presented him with a glorious chance, somehow shooting over from six yards.
Sven Botman shot into the side-netting after Newcastle sliced through the Saints defence yet again.
Che Adams almost caught Newcastle with a sucker punch, but the Southampton substitute shot wastefully at Pope after breaking clean through on goal.
Pope came to Newcastle's rescue with another important save as he clawed away Adams' shot on the turn.
Newcastle finally took the lead in the 73rd minute when substitute Alexander Isak accelerated away from Caleta-Car for a low cross that Joelinton smashed home from close-range to the delight of thousands of Newcastle fans behind the goal.
Southampton thought they had equalised just two minutes later, but Armstrong's finish from inside the six-yard box was disallowed for his handball.
It was hard on former Newcastle striker Armstrong as the ball inadvertently bounced onto his arm off Botman as the pair challenged for a cross.
Southampton's frustration was clear and Caleta-Car was shown a second yellow card in the 86th minute for a needless shove on Bruno Guimaraes.