Guimaraes pulling the strings again with a precise throughball for Isak, who rounds Bazunu, but the angle narrows and he can only find the side-netting.
Salisu drags back Isak and goes into the book.
90' +2
The Magpies push for a second goal and a patient build-up culminates in Guimaraes finding Murphy, who shoots into the side-netting.
90' +1
There are going to be five additional minutes at the end of this game. Can Newcastle find a second goal for breathing space ahead of next week's return leg at St James' Park?
89'
Trippier goes for goal from distance with an ambitious free-kick. However, it does not dip enough and goes over.
88'
J. Bednarek enters the game and replaces K. Walker-Peters.
The Saints turn straight to the bench and introduce centre-half Bednarek in place of Walker-Peters.
86'
Bruno Guimarães gets yellow.
D. Ćaleta-Car gets a second yellow card and is sent off.
RED CARD! The Saints are down to 10 men as Caleta-Car receives his marching orders. The centre-half takes out Saint-Maximin, who had embarked on a jinking run towards the edge of the area. He can have no complaints.
Yellow Card Bruno Guimarães Rodriguez Moura
84'
Lyanco gets yellow.
A. Saint-Maximin gets yellow.
Lyanco drags back Guimaraes and has his name taken by the referee.
Saint-Maximin goes into the book for his part in a brief scuffle after Lyanco's foul on Guimaraes.
82'
R. Lavia enters the game and replaces I. Diallo.
A change for the Saints sees Lavia introduced to replace Diallo.
78'
J. Murphy enters the game and replaces M. Almirón.
Newcastle turn to the bench with Almiron replaced by Murphy.
Minute
Description
73'
Joelinton has scored a goal for Newcastle United! Assist by A. Isak.
Isak brilliantly burst away from his marker before putting the ball on a plate for Joelinton.
JOELINTON!!! 1-0 NEWCASTLE! The Magpies strike first! Picking up the ball on the right wing, a wonderful turn of pace sees Isak accelerate away from Caleta-Car. He then flashes the ball into the six-yard area, where Joelinton arrives to apply the finishing touch and send the Toon Army into ecstasy.
72'
Following a Newcastle counter, Burn sends a low ball into the box, which Longstaff tries to flick towards goal. However, Southampton block and clear.
70'
K. Trippier gets yellow.
Trippier catches Edozie late and is booked by the referee.
69'
We are approaching the last 20 minutes at St Mary's, where we remain goalless. Can either side break through and claim a crucial advantage ahead of next week's second leg.
68'
A. Saint-Maximin enters the game and replaces J. Willock.
A. Isak enters the game and replaces C. Wilson.
67'
Isak also enters the fray with Wilson the player to make way.
Newcastle make a double-change. The first sees Saint-Maximin introduced in place of Willock.
63'
Ward-Prowse goes for the spectacular as he connects with Walker-Peters' cross. Although, the Saints skipper is always stretching and is never going to trouble Pope.
61'
The noise level of anticipation increases around St Mary's as Edozie breaks away from Trippier. However, his final ball is disappointing and Burn cuts it out.
57'
C. Adams enters the game and replaces S. Mara.
S. Edozie enters the game and replaces M. Oršić.
Armstrong embarks on a strong run and works space for a shot from a tight angle. However, he cannot keep it down.
The other sees Mara make way for Edozie.
Substitution Mislav Oršić Samuel Ikechukwu Edozie
56'
Howe will be pleased that Newcastle are creating these opportunities, but he will hope the Magpies are not made to regret not taking them.
54'
The visitors continue to threaten with Almiron getting away from Mara before crossing. Botman connects at the far post, but hits the side-netting from a tight angle.
52'
Away from this competition, Newcastle are well on course for a top-four finish in the Premier League. It is exactly 20 years since they last achieved the feat under the late, great Bobby Robson.
50'
Following a dogged run into the box by Armstrong, the ball loops high into the area. With headlines in his sight, Mara goes for the spectacular acrobatic effort, but it is not troubling the goal.
47'
Once again, Newcastle counter with Almiron's pace proving a real handful for Southampton. He cuts the ball across to the edge of the area, where the onrushing Longstaff is unable to keep his first-time shot down.
46'
Southampton get the ball rolling once more in the second half.
45' +7
HALF-TIME: SOUTHAMPTON 0-0 NEWCASTLE UNITED
45' +4
A. Armstrong enters the game and replaces M. Djenepo.
Djenepo is replaced by former Newcastle striker Armstrong, who made 17 appearances for the Magpies at the start of his career.
44'
K. Walker-Peters gets yellow.
Walker-Peters takes too long with a throw-in and has his name taken by the referee.
42'
Space opens for Alcaraz to try his luck from distance. The debutant imparts plenty of power into his ambitious attempt, and Pope is forced to help it away from goal.
41'
A let-off for Southampton, who allowed Newcastle to break down the left flank far too easily. The Saints cannot afford their opponents too many opportunities to hurt them on the counter.
37'
C. Alcaraz gets yellow.
Alcaraz drags back Guimaraes and goes into the book.
36'
This is the latest semi-final Trippier has played in during his career. The England full-back has also appeared at this stage of a World Cup, European Championship and Champions League.
30'
Trippier sends a free-kick delivery into the box from the right. However, Southampton are alert and deal with the danger.
28'
D. Ćaleta-Car gets yellow.
Caleta-Car receives the game's first yellow card after a late challenge on Almiron. The Southampton defender can have no complaints.
26'
A certain Alan Shearer - a brilliant servant of both clubs - watches on from the stands. The former Newcastle striker was part of the side that reached the FA Cup semi-finals in 2005, before losing 4-1 to Manchester United.
19'
Newcastle threaten again and Trippier whips in a fierce cross from the left flank. However, Bazunu is alert and punches clear.
17'
Jones barks out instructions to his team from the touchline. The Saints have been second best so far, but are yet to be breached.
15'
A rare venture forward from Southampton sees Ward-Prowse whip in a cross from the right. Alcaraz looks to connect, but a well-timed Schar sliding challenge thwarts him.
11'
Newcastle go direct as Schar seeks out Wilson with a long ball forward, but the England striker is unable to get it under control and Bazunu comes out to collect.
9'
That stoppage following Schar's injury has certainly disrupted Newcastle's rhythm, with the visitors not quite flowing the same as they were during the early stages of this contest.
4'
The visitors continue to threaten and a patient build-up culminates in Longstaff sending a brilliant ball across the face of goal. Unfortunately, none of his team-mates react quickly enough and Southampton survive.
3'
An early chance for the Magpies, who quickly counter with Almiron leading the charge. He finds Willock in plenty of space, but the midfielder gets it all wrong and sends his first-time shot high into the stand.
1'
The referee blows his whistle and Newcastle get us under way.
SUBS: Karl Darlow, Jamaal Lascelles, Allan Saint-Maximum, Matt Ritchie, Jamal Lewis, Alexander Isak, Javier Manquillo, Jacob Murphy, Elliot Anderson.
NEWCASTLE UNITED (4-3-3): Nick Pope; Kieran Trippier, Fabian Schar, Sven Botman, Dan Burn; Joe Willock, Bruno Guimaraes, Sean Longstaff; Miguel Almiron, Callum Wilson, Joelinton.
SUBS: Willy Caballero, Ainsley Maitland-Niles, Adam Armstrong, Che Adams, Romain Perraud, Samuel Edozie, Mohamed Elyounoussi, Jan Bednarek, Romeo Lavia.
SOUTHAMPTON (4-2-3-1): Gavin Bazunu; Lyanco, Duje Caleta-Car, Mohammed Salisu, Kyle Walker-Peters; Ibrahima Diallo, Carlos Alcaraz; Mislav Orsic, James Ward-Prowse, Moussa Djenepo; Seko Mara.
Southampton have beaten Cambridge, Sheffield Wednesday, Lincoln and Manchester City to reach the semi-finals of this tournament for a fourth time. Meanwhile, Newcastle have overcome Tranmere, Crystal Palace, Bournemouth and Leicester to reach the last four of any competition for the first time in 18 years.
Newcastle are gearing up for only their second League semi-final and first since reaching the 1975-76 final - the same season that saw Southampton win their only major honour by lifting the FA Cup.
Hello everyone and welcome to live text coverage of the EFL Cup semi-final first leg between Southampton and Newcastle United at St Mary's.
The players are coming out onto the pitch and we are just moments away from kick-off at St Mary's.
It was a generally open first half, albeit lacking that piece of quality required to break the deadlock. Both sides will look to find it when this contest resumes.
That's all for today. Thank you for following our live coverage. Until next time, goodbye.
Both sides will do battle again at St James' Park next Tuesday, where the aggregate winners will secure their place at Wembley. Before then, Southampton are in FA Cup fourth-round action at home to Championship side Blackpool on Saturday, with Newcastle enjoying a rest following their surprise third-round defeat to Sheffield Wednesday of League One.
Commentary
More…