Kelechi Iheanacho was Leicester’s FA Cup saviour again as the Foxes squeezed past Walsall.
The substitute’s deflected strike clinched a 1-0 win to send the visitors into the fifth round and spare Youri Tielemans’ blushes.
The skipper missed a second-half penalty before Iheanacho ended the Saddlers’ stubborn resistance.
Iheanacho, who also scored the winner in the 1-0 third-round victory at Gillingham, now has 17 goals in 23 FA Cup appearances.
It was a slog for Leicester with Walsall edging the first half but Michael Flynn’s men never seriously tested Daniel Iversen.
The League Two side can still be proud of their efforts even if Flynn was unable to add another upset to the list.
His cup pedigree involves knocking Leicester out of the FA Cup in 2019 while his Newport side also beat Leeds and Watford, took Tottenham to a replay and Brighton and Newcastle to penalties.
A 4-1 FA Cup defeat to Manchester City even sparked a friendship with Pep Guardiola which Flynn cherishes and the upset expert was hunting another scalp.
His side – with only two league defeats since September – went at Leicester with relish and Iversen turned Tom Knowles’ early low effort away.
They were helped by the Foxes, with fit-again James Maddison starting for the first time since November, lacking the cohesion and concentration needed for this kind of cup tie.
Loose passes stunted any momentum and they were hassled by the lively Saddlers with Maddison’s booking for dissent underlining the visitors’ frustrations.
Walsall won the physical battles, committing to the challenges Leicester were clearly not used to in the top flight, and had every reason to be happy with their first-half display.
That said, the Foxes still found some brief openings with Harvey Barnes miscuing at the far post and Patson Daka firing over after a sharp turn but there was little to suggest they would have anything other than an uncomfortable afternoon in the shadow of the M6.
A rough and tumble cup tie had the 2021 winners scrambling, Tielemans unable to make a mark and Barnes cutting a lonely figure on the left with Leicester’s big names failing to step up before the break.
That there was no zip from the Foxes owed much to Walsall’s refusal to give them an inch but the Saddlers gifted the visitors a golden chance two minutes after the restart.
Joe Low’s poor touch allowed Daka to nip in ahead of Isaac Hutchinson, who sent him tumbling in the box, and although referee Gavin Ward initially gave a free-kick he eventually awarded the penalty.
It was the perfect chance for Leicester to grab hold of a tie which had threatened to slip away but Tielemans’ poor spot-kick hit the post.
Walsall quickly responded and Andy Williams volleyed over with the game sparking to life and Leicester finally found their mojo.
Suddenly, the Saddlers were in danger of being overrun and needed goalkeeper Owen Evans to deny Barnes, Tielemans and Daka.
But Leicester finally had control and made it count with 22 minutes left.
Patient build up involving Nampalys Mendy, Timothy Castagne and Tielemans ended with Mendy finding Iheanacho.
The striker was allowed to turn onto his left foot and his 20-yard effort took a wicked deflection off Brandon Comley to loop over Evans.