Everton loanee Besic whipped home his first Blades goal on his 13th appearance, before Norwood wrapped up the fourth-round victory amid an insipid clash at The Den.
Aiden O’Brien scuffed a glorious early chance for Millwall and the hosts never recovered, with two clinical finishes sufficient to put Chris Wilder’s men in the hat for the fifth round draw.
— Sheffield United (@SheffieldUnited) January 25, 2020
South Bermondsey has played host to seven FA Cup giant-killings since 1993, with the Lions well versed in a Premier League mauling.
This throwback tie had all the hallmarks of another entry into those lengthy annals, save for any kind of killer blow from the hosts.
A threadbare pitch thanks to a faulty drainage system, floodlights on in broad daylight and the typically hostile atmosphere; all these and more left the Blades often lacking interest or impetus.
But boss Wilder’s in-form men coped comfortably enough in the event, as Millwall struggled for any bite in attack.
Besic stroked wide from 16 yards as the Blades eyed an early breakthrough but the visitors were reeling when the vastly-experienced Phil Jagielka was caught out wholly unnecessarily when misjudging a header.
The former Everton man raced out but missed the ball, leaving a gaping hole for O’Brien to race through, cut inside the cover – but scuff his shot straight at Bartosz Bialkowski.
Millwall almost slumped off the pace in response to a gilt-edged chance missed but such was the paucity of quality on display that United were unable to take advantage before the break.
Jagielka then headed high and wide after working himself free at a corner, but a distinctly underwhelming half ended scoreless.
Both sides at least upped the intensity after the break – and a surprise moment of accuracy broke the deadlock.
Callum Robinson’s lofted ball let Sharp apply the squeeze on the Lions, with the skipper finding Besic on the overlap.
The Bosnia midfielder checked inside, opened his body and delivered a textbook curling finish.
Norwood quickly slotted the match-sealing second after a fine tee-up from skipper Sharp, as Millwall slipped well off the pace at the end.
Simple, effective, decisive – two finishes boasting all the qualities missing both before and afterwards at The Den.