Arsenal's young attackers repaid manager Mikel Arteta's faith by getting the goals to see them past Bournemouth with a 2-1 win on Monday night.
Arteta was back at the same ground he began his Arsenal tenure at and saw his side take an early lead when 18-year-old Bukayo Saka lashed the ball home from a tight angle.
And Saka was vital to the Gunners' second goal too crossing from the left for Eddie Nketiah, just 20 years old himself, to finish and put the visitors in control.
Bournemouth did eventually get an injury-time goal via Sam Surridge but couldn't get another to force the replay as Arsenal prepare for another south coast visit in the fifth round at Portsmouth now.
No stopping that β‘οΈ#EmiratesFACup #BOUARS pic.twitter.com/QFOxbNT30s
— The Emirates FA Cup (@EmiratesFACup) January 27, 2020
SUNDAY
Liverpool will need a replay to settle their fourth round tie with Shrewsbury following a dramatic 2-2 draw, including a second half brace from substitute Jason Cummings.
Teenager Curtis Jones, who scored a wonder goal at Anfield to see off Everton in the third round, found the net again with a composed finish in the bottom right corner.
The Shrews looked threatening against Jurgen Klopp's much-changed side until Donald Love inadvertently turned the ball into his own net less than 30 seconds after the restart.
But there was another twist in the tale when Yasser Larouci brought down Josh Laurent and substitute Cummings scored from the spot only to grab an equaliser with 15 minutes to play.
Did somebody say MAGIC OF THE CUP?! πππ#EmiratesFACup #SHRLIV pic.twitter.com/x9ncMafa77
— The Emirates FA Cup (@EmiratesFACup) January 26, 2020
Klopp then introduced the big guns off the bench with Mohamed Salah and Roberto Firmino joining the action but neither could match Cummings' contribution as the League One side held on for a lucrative trip to Anfield.
Elsewhere Manchester United earned their biggest away victory for more than 20 years as they swept Tranmere Rovers aside 6-0.
No less than three United defenders got their names on the scoresheet in the first half as the away side nothced five of their goals in the opening 45 minutes.
Harry Maguire set the ball rolling with a screamer and his first goal for the club before Diogo Dalot did exactly the same and Jesse Lingard added a third.
Phil Jones, who hadn't scored since March 2014 when David Moyes was in charge, headed in a fourth while youngster Mason Greenwood added a second-half penalty.
PICK THAT OUT, @AnthonyMartial π₯#EmiratesFACup #TRAMUN pic.twitter.com/i9zSwgjbje
— The Emirates FA Cup (@EmiratesFACup) January 26, 2020
And holders Manchester City cruised into the fifth round with a 4-0 win over Fulham at the Etihad.
The Cottagers lost their captain early on when Tim Ream was sent off for ulling back Gabriel Jesus in the box with Ilkay Gundogan scoring the resulting penalty.
Bernardo Silva then doubled City's advantage dancing his way to the edge of the box before smashing the ball past Marek Rodak in the Fulham goal.
Jesus then added two second-half headers to complete the rout, for a side who have averaged five goals per game in home FA Cup matches during Pep Guardiola's reign.
72' Gabriel Jesus heads home for @ManCity [Ctrl-C]
— The Emirates FA Cup (@EmiratesFACup) January 26, 2020
75' [Ctrl-V] Gabriel Jesus heads home for @ManCity #EmiratesFACup #MCIFUL pic.twitter.com/I6ZsiqMam5
SATURDAY
West Bromwich Albion caused an upset for West Ham as Slaven Bilic returned to haunt his former side with a 1-0 win.
Conor Townsend bagged the only goal of the game, and his first for the Baggies since joining in 2018, when he steered his effort past the outstretched Darren Randolph on nine minutes.
And Bilic's side held on despite losing defender Semi Ajayi for a second yellow with 20 minutes left to secure a spot in the fifth round.
Norwich City reached the fifth round for the first time since 2011-12 as they beat fellow top-flight opponents Burnley 2-1 at Turf Moor.Slaven BiliΔ returns to the Olympic Stadium to haunt his former club in the #EmiratesFACup fourth round π» pic.twitter.com/FeG0DQXoJV
— The Emirates FA Cup (@EmiratesFACup) January 25, 2020
The Premier League's bottom side took the lead after a goalless first half via a Grant Hanley header before Josip Drmic scored on his first Canaries start three minutes later.
Erik Pieters did pull one back for the hosts but it wasn't enough to stop the Clarets crashing out.
In Saturday's early kick-off Leicester City defended a 1-0 lead for almost 90 minutes as they edged past Brentford and into the hat for the fifth round.
The Foxes proved their top-flight credentials within the first three minutes when Dennis Praet's 50-yard defence-splitting through ball found James Justin, who squared the ball for Kelechi Iheanacho to finish.
Ayoze Perez had the chance to double the lead just before half time but the Bees just couldn't grab an equaliser as the curtain came down on Emirates FA Cup action at Griffin Park.
Chelsea squeezed past Hull City with a 2-1 victory in Saturday evening's late kick-off.
Michy Batshuayi put the Blues ahead early on before Fikayo Tomori headed home to put Frank Lampard's side in full control.
But Kamil Grosicki's deflected free-kick made for a nervous last ten minutes before the final whistle blew at KCOM Stadium.
And Sheffield United proved too much for Championship side Millwall as the Blades kept their name in the hat with a 2-0 victory.Tomori nods home from close range to double the visitors advantage.
— The Emirates FA Cup (@EmiratesFACup) January 25, 2020
Game, set and match?#EmiratesFACup pic.twitter.com/1KnxBWRPTk
Everton loanee Muhamed Besic broke the deadlock with just over an hour played with a curling long-range effort into the bottom corner.
And Oliver Norwood put the tie beyond doubt when netted a long-ranger of his own with ten minutes left on the clock.
Meanwhile Tottenham Hotspur and Southampton will require a replay after their 1-1 draw at St Mary's.
Spurs went ahead through Son Heung-min just before the hour mark but Saints looked threatening throughout the game and eventually got their goal when substitute Sofiane Boufal scored his first goal for two years.
And Newcastle will also need to take their tie back to Oxford United after a stalemate at St James' Park.
Portsmouth produced one of the performances of the round with a 4-2 win over Barnsley.
Ben Close turned home from close range to give Pompey the lead and John Marquis doubled their advantage from a corner on the stroke of half time.
The Tykes may have been knocked out but Cauley Woodrow produced one of the goals of the round with a swerving effort from 30-yards to halve the deficit.
But it wasn't enough as Ronan Curtis immediately re-established Pompey's two-goal lead before Christian Burgess added a fourth and Conor Chaplin tapped home late.
Cardiff City and Reading will also need a replay following their 1-1 draw.
No sooner had Callum Paterson put Cardiff ahead from close range than Yakou Meite equalised down the other end - all before ten minutes had been played.
The Ivorian celebrated by dedicating the goal to his father, who passed away recently.
A beautiful moment for Yakou Méïté as he dedicates his #EmiratesFACup fourth round goal to his late father β€οΈ pic.twitter.com/q5QY5N5yU1
— The Emirates FA Cup (@EmiratesFACup) January 25, 2020
And Coventry and Birmingham will return to St Andrew's for a second game after playing out a stalemate.
FRIDAY
On Friday night, Sheffield Wednesday edged past QPR and into the fifth round with a 2-1 win despite a late scare from the Hoops.
The Owls made the most of a quick throw in to open the scoring as Sam Hutchinson found Morgan Fox with space in the box.
The Welshman allowed the ball to bounce in front of him before stabbing an effort on goal from an acute angle as the ball squirmed under Joe Lumley and over the line.
It wasn't until extra-time that the next goal came when Sam Winnall doubled the visitors' lead before Nahki Wells capitalised on a Cameron Dawson mistake to earn his side a late consolation.
Signed, sealed, delivered. #EmiratesFACup @swfc pic.twitter.com/pSHHdDfhfR
— The Emirates FA Cup (@EmiratesFACup) January 24, 2020
Meanwhile, in Friday night's other game, Northampton Town and Derby County played out a 0-0 draw at Sixfields.
The Cobblers' captain Charlie Goode was lucky to avoid an early dismissal when he brought down Jack Marriott bearing down on goal.
Northampton restricted Wayne Rooney's Derby to aerial football as Sam Hoskins caused trouble down the right flank but couldn't produce any quality in the final third.
And Derby fans were given a faint glimpse of avoiding a replay when Rooney was stood over a free-kick in the final minute but his delivery was dealt with by Keith Curle's side, who now face a trip to Pride Park.