The Lowdown: Ralph Hasenhüttl's Saints
Wembley Stadium is the venue for the last four encounter between the Foxes and the Saints as two sides vying for a spot in the final of the prestigious competition meet for the second time this season.
By defeating Stoke City, Brentford, Brighton & Hove Albion and Manchester United in previous rounds, City booked a place in the semi-finals for the first time since 1982.
Their South Coast opponents, meanwhile, reached this stage in 2017/18, losing out to Chelsea.
This season, they have knocked out Shrewsbury Town, Arsenal, Wolverhampton Wanderers and Bournemouth and, ahead of Sunday's clash, LCFC.com takes a look at the how the Saints shape up...
The team
After an 11th-place finish in 2019/20, there was little summer upheaval at St. Mary's Stadium, with the spine of the side remaining from the last campaign, with the exception of Tottenham-bound midfielder Pierre-Emile Højbjerg.
There is plenty of English talent within their ranks, such as Alex McCarthy, Ryan Bertrand, James Ward-Prowse, Nathan Redmond and Danny Ings.
Ings remains the club's top scorer in all competitions with 10 goals to his name from 27 games, following 22 goals in 2019/20, which meant he narrowly missed out on the Premier League Golden Boot to Jamie Vardy.
The England forward is the only player to have hit double figures for Southampton this term, although set piece specialist Ward-Prowse is not far behind with eight strikes from midfield and five assists, which places him, alongside Stuart Armstrong, as the club's leading assist maker.
Southampton strengthened their English contingent in the summer with the permanent signing of Kyle Walker-Peters and the return of Theo Walcott, 14 years after he left the club to join Arsenal.
The Saints also bolstered their attacking options further in the January transfer window with the loan signing of Liverpool midfielder Takumi Minamino and the Japan international has since contributed two goals in his first six appearances for the club.
The manager
Former Austria international striker Ralph Hasenhüttl joined the Saints in December 2018, following spells in charge of German sides SpVgg Unterhaching, VfR Aalen, FC Ingolstadt 04 and Red Bull Leipzig.
He won promotion with both Aalen and Ingolstadt, while Hasenhüttl also led Leipzig to a second-place finish in the Bundesliga during his debut season as their manager, runners-up to Bayern Munich.
As a player, at Austria Wien, he won the Austrian Bundesliga three times, and the Austrian Cup twice, while he also picked up another league and cup trophy in his home nation with Austria Salzburg shortly after.
During his playing career, he played for his hometown club Grazer AK, based in Graz, Belgian outfits Mechelen and Lierse, and German sides FC Cologne, SpVgg Greuther Fürth and finally Bayern Munich II.
Following a 16th-place finish in 2018/19, Southampton made a significant improvement the next campaign, finishing 11th in the Premier League standings, remaining unbeaten in their final seven fixtures, including a 1-0 home victory over Manchester City.
Form guide
Southampton occupy a mid-table position in the Premier League table after a topsy-turvy season which, at one stage, saw the Saints at the top of the standings.
There have been some memorable results to date, including recording a 1-0 win over the reigning Premier League champions Liverpool, when Danny Ings found the net against his former club.
Ralph Hasenhüttl's side also enjoyed a seven-game unbeaten run, which included a 3-3 draw at Chelsea and coming out on the right side of a 4-3 thriller against Aston Villa.
During their last home fixture, Southampton came from two goals down to defeat Burnley 3-2 thanks to goals from Stuart Armstrong, Ings and Nathan Redmond. On Monday, meanwhile, Hasenhüttl's men were beaten 3-0 at West Bromwich Albion.
In the FA Cup, the Saints saw off Sky Bet League 1 side Shrewsbury Town 2-0 in the third round at St. Mary's Stadium, followed by a terrific 1-0 win over Arsenal at the same venue.
Wolves were also overcome without conceding, this time with a 2-0 scoreline at Molineux Stadium, before Championship outfit AFC Bournemouth were comfortably beaten 3-0. The Saints have scored eight goals and kept four clean sheets out of four so far in this season's competition.
Previous encounters
Leicester took all three points from the last Premier League meeting between the two sides, at King Power Stadium in January 2021. James Maddison's first-half opener was followed by Harvey Barnes' late second, to wrap up a 2-0 victory for the Foxes.
City's most memorable visit to Southampton's home of St. Mary's Stadium, meanwhile, came in October 2019 when the Club equalled a 24-year record for the biggest-ever Premier League victory.
Jamie Vardy and Ayoze Pérez netted hat-tricks in the 9-0 success over the Saints, which also broke the record for the biggest away win in the top flight.
Southampton's most recent triumph in the fixture, however, came in January 2020. The Foxes took the lead via Dennis Praet's 14th-minute strike before Stuart Armstrong hit back for the Saints and Danny Ings scored a late winner.
The trophy cabinet
Southampton’s most significant honour came in 1976, when they lifted the FA Cup, following a 1-0 victory over Manchester United, thanks to a solitary strike from Bobby Stoke with seven minutes to play.
In 1984, they finished as runners-up in England’s top flight, finishing just three points behind Liverpool, while they won the third tier in 1960.
Their back-to-back promotions in 2010/11 and 2011/12 eventually led to them making a return to the Premier League after a seven-season absence.
Immediately prior to that recent success, they won the EFL Trophy by beating Carlisle United at Wembley Stadium in front of over 73,000 fans in March 2010.
The stadium
St. Mary’s Stadium was opened in August 2001, replacing the Dell – an iconic ground which the Saints played at for over a century. With over 32,500 seats, it has a slightly higher capacity than King Power Stadium, and has played host to four senior England internationals.
The first saw the Three Lions draw 2-2 with Macedonia in 2002, while victories over Norway, Italy and Kosovo have also taken place on the same turf.
The fixtures
Southampton are immediately back in Premier League action just three days after the Wembley semi-final, facing a trip to Tottenham Hotspur on Wednesday 21 April (6pm kick-off).
The Saints then meet Leicester once more, this time at St. Mary's Stadium in the Premier League, on Saturday 1 May, followed by visiting Anfield and Liverpool on Saturday 8 May (both 3pm kick-offs).
The league calendar concludes with matches against Fulham (H), Leeds United (H) and West Ham United (A).
All times GMT.