The Nigeria international comes into the game as one of the in-form players in English football having scored nine goals in his last six games in all competitions.
It's the type of run that will strike fear into Ralph Hasenhuttl and his players, and it's one that drew praise from Southampton cult hero Francis Benali while speaking exclusively to GIVEMESPORT ahead of the game.
The former Saints full-back spent more than 16 years with the club between 1987 and 2004, writing his name into club club folklore in the process.
Benali was part of the Southampton squad that last reached an FA Cup final in 2003 and, naturally, he is hoping the south coast outfit can repeat that feat and overcome the challenge of Leicester on Sunday.
However, he is acutely aware of the quality Brendan Rodgers has at his disposal.
Citing Iheanacho as a key dangerman for Southampton to be wary of, Benali lauded the striker's almost intuitive, care-free finishing ability of late.
"Iheanacho's form is just outstanding, and he'll be coming into the game full of confidence. You saw his goals against West Ham. It's so natural for him, there's no effort to them is there. That's the confidence of the run that he's on at the moment."
The 24-year-old has filled the goal scoring void left by Jamie Vardy's dry spell and given the Foxes a potent attacking outlet at a crucial juncture in the season.
Utilising his ability to drop into the hole and link the play while simultaneously offering a poacher's threat in the penalty area, Iheanacho finally seems to be delivering on the promise that defined the formative stages of his career.
But Benali has been thoroughly impressed by an array of Leicester players this season and commended the work Rodgers has done since taking the reins at the King Power Stadium.
Despite the obvious respect he has for the Foxes, Benali tipped his former club to get the job done with a narrow, hard-fought 2-1 win.
"Under Brendan Rodgers, they're an improving side. They are a very, very good footballing team. I don't see any real weakness in the team.
"Youri Tielemans in midfield is just an outstanding performer and is a big part of how they press and look to win the ball back. So there'll be some fascinating matchups on Sunday.
"I'm not for one minute underestimating the size of the task that lies ahead of Saints, but I've got to back my team to win and get to the final!
"It's hard to put an actual prediction on it, but I think we'll we'll have to score more than one goal to get through. I'm gonna have to go 2-1."
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