Leicester City's Nampalys Mendy fired home the decisive spot kick as they beat Southampton 6-5 on penalties after a 0-0 draw, on Tuesday, to book a League Cup quarter-final with holders Manchester City.
Southampton had a Steven Davis goal disallowed by the VAR late in the second half and hit the crossbar through Manolo Gabbiadini in stoppage time with the match going straight to penalties without extra time.
After 10 successive penalties found the net, Gabbiadini's weak effort was saved by Leicester keeper Danny Ward and Mendy slotted home the winner.
The fourth-round fixture was originally scheduled for last month but was postponed after the Leicester chairman Vichai Srivaddhanaprabha was killed in a helicopter crash.
Southampton's 18-year-old striker Michael Obafemi had the game's first real chance when he toe-poked wide after 22 minutes, but it was his miss in the second half that is likely to play on his mind for a little longer.
Nathan Redmond's effort came down off the crossbar and dropped at Obafemi's feet, but he somehow contrived to prod wide.
Southampton thought they had taken the lead with eight minutes remaining after Redmond bundled his way into the box before Davis swept home.
His effort, however, was chalked off by the Video Assistant Referee for a handball against Redmond after the ball had cannoned into the Southampton winger's arm as he battled into the area.
Gabbiadini hit the bar with a dipping, curling free kick in stoppage time before Southampton's luck deserted them further in the shootout.
Leicester will be at home to City in the last eight.
Arsenal's Europa League clash moved to Kiev due to security concerns
Arsenal's Europa League match against Vorskla Poltava on Thursday has been moved to Kiev due to security concerns following the introduction of martial law in Ukraine, European soccer's governing body UEFA has announced.
Politicians in Ukraine this week approved a proposal to introduce martial law in areas most vulnerable to an attack following the capture of three Ukrainian vessels by Russia over the weekend.
Arsenal were due to play their Group E clash with Vorskla in Poltava's Oleksiy Butovsky Stadium. However, UEFA said that its emergency panel met on Tuesday and decided to move the match to Kiev's Olympic stadium.
"UEFA will continue to monitor and assess the security situation in Ukraine in the coming days before making any decision on potentially relocating other matches," the body said in a statement.