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.
Iheanacho came off the bench to send the Foxes through to the fifth round.
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