Substitute Iheanacho finished emphatically from Jamie Vardy's pass with 16 minutes left to give The Foxes the reward their incessant second-half pressure merited to set up a tense second leg at Villa Park.

Villa, struggling with injuries after goalkeeper Tom Heaton and striker Wesley were ruled out for the season, defended with organisation and resilience to protect the lead given to them after 28 minutes when Frederic Guilbert stole in at the far post to meet Anwar El Ghazi's cross.

Ezri Konsa's header also struck the bar for Villa but Leicester applied most of the pressure with keeper Orjan Nyland saving twice from James Maddison and Vardy, who also shot just wide late on, before he was beaten by Iheanacho's powerful strike from 12 yards.

The second leg at Villa Park takes place on Tuesday, 28 January.

Grealish shines in front of Southgate

Jack Grealish previously played for the Republic of Ireland at youth level before transferring his allegiance to England

England manager Gareth Southgate was in the stands at The King Power Stadium to cast his eye over several players as he finalises his Euro 2020 plans.

Villa defender Tyrone Mings and Leicester pair James Maddison and Ben Chilwell have already won full caps - so Southgate will have been paying particular attention to Jack Grealish, who has been a key figure for Dean Smith's side this season.

Grealish is yet to make the breakthrough to full England status and his midfield battle with Maddison, who is yet to fully convince Southgate, was an intriguing sub-plot to this semi-final.

And the Villa captain did not disappoint, surely pressing his claims for inclusion in England's squad and the opportunity to put himself in contention for this summer's Euros.

Villa spent much of the game on the back foot but Grealish was composed and strong on the ball when he got the chance, always looking for the chance to play the decisive pass on the rare occasions they were able to build pressure.

Maddison is currently ahead of Grealish in Southgate's pecking order, but this classy display from the 24-year-old will have given Southgate food for thought as Villa set up a platform to give themselves a real chance of reaching the EFL Cup Final against either Manchester City or Manchester United.

Leicester's patience rewarded

Leicester manager Brendan Rodgers is unbeaten in his past 31 domestic cup games (W27 D4), although this is his first home draw in this run since September 2015 when manager of Liverpool (1-1 against Carlisle United in the League Cup)

Leicester City were not quite at their fluent best that has taken them into second place in the Premier League, forcing their way between runaway leaders Liverpool and reigning champions Manchester City.

And yet, despite this, the Foxes showed real determination and patience to maintain the pressure until marksman Vardy turned creator with an astute pass that released Iheanacho for his late leveller.

There were occasions when the home crowd, largely supportive, became impatient as Leicester probed but they stayed true to the principles of manager Brendan Rodgers and no-one apart from Villa could complain about their equaliser.

Rodgers would have wanted victory from this home leg but he looked satisfied at the final whistle, clearly believing this is a result Leicester City can work with at Villa Park, where their pace and power on the break - spearheaded by Vardy - may be an even bigger weapon than it was here, as it was in their recent 4-1 league victory.

Man of the match - Jack Grealish (Aston Villa)

Jack Grealish has been a key figure in Villa's team this season and once again underlined his importance to his side

'He has really come to the fore' - reaction

Leicester boss Brendan Rodgers: "Kelechi is a big talent. He didn't play a lot of football at Manchester City and it takes a bit of time to adapt.

"But since I've come in his confidence has grown and grown and we believe in him and believe in his talent and this season he has really come to the fore.

"He works so hard every day. He's either making a goal or scoring a goal now and he works so hard in his pressing game. He was a threat when he came on against Villa and I'm delighted for him."

Aston Villa manager Dean Smith: "It should be a good second leg, all square and a boisterous crowd, a full house.

"It wasn't the performance I wanted, Leicester were the better team but we defended well at times. We have to be honest, they created chances as well. We were loose on the ball tonight, we've got to do better.

"I'm certainly content with a draw, just not the performance. We gave away a farcical goal. Ezri Konsa has got brain dazzled. A disappointing goal but it sums up some of our performance on the night. We did get in a lot of tackles and blocks."

El Ghazi shines for Villa again - stats

• Villa have scored 17 League Cup goals this season - their most since 2012-13, with Villa last scoring more in the 1999-00 campaign (18).
• Villa have not kept a clean sheet on the road in all competitions in their last 17 games, last doing so against Bolton Wanderers in April 2019.
• Iheanacho has been directly involved in seven goals in his five competitive appearances against Aston Villa (five goals, two assists) - more than any other opponent in his professional club career.
• Vardy has provided five assists in his 22 appearances in all competitions this season; as many as he got for Leicester City in the previous two campaigns (five assists in 78 apps).
• El Ghazi has been directly involved in 11 goals in all competitions for Aston Villa this season (five goals, six assists); only Grealish has more for the Villans (14).
• Guilbert's goal in the 28th minute was Aston Villa's only shot on target in the match. In fact, they only recorded three shots in the entire game - the lowest total they have registered in all competitions since May 2016 against Newcastle United (two shots).
• No player had more shots (eight), shots on target (two) or created more chances (four) than Leicester's Maddison in this match, with Grealish having zero shots and recording just one key pass by comparison.

What's next?

Leicester are home to Southampton in the league on Saturday (15:00 GMT) and Villa host Manchester City on Sunday (16:30 GMT)