London - Aaron Ramsey and Olivier Giroud scored as Arsenal started their FA Cup defence by coming from behind to defeat Sunderland 3-1 in the third round on Saturday.
Arsenal were joined in round four by Premier League title rivals Manchester City, who won 3-0 at Norwich City, but Southampton and Newcastle United were both eliminated and West Bromwich Albion survived a huge scare.
Sunderland took a 17th-minute lead at the Emirates Stadium through Jeremain Lens, but Joel Campbell equalised eight minutes later before second-half goals by Ramsey and Giroud gave Arsene Wenger's men victory.
Premier League leaders Arsenal are seeking to become the first team to win three FA Cups in a row since Blackburn Rovers between 1884 and 1886.
A side showing five changes fell behind when Lens picked Laurent Koscielny's pocket and fired home, but minutes later Theo Walcott teed up Campbell to tuck away the equaliser.
Substitute Ramsey made it 2-1 in the 72nd minute after a one-two with Hector Bellerin and Bellerin then teed up Giroud for Arsenal's third goal four minutes later.
Manchester City strolled through at Carrow Road, where Sergio Aguero put the visitors ahead in the 16th minute with a driving run and emphatic shot.
Aguero set up 19-year-old strike partner Kelechi Iheanacho for City's second goal on the half-hour and substitute Kevin De Bruyne wrapped up victory 12 minutes from time.
Southampton and Newcastle both fell at the first hurdle, but could at least console themselves that they were beaten by fellow Premier League teams.
Wilfried Zaha's 68th-minute goal gave Crystal Palace a 2-1 win at Southampton, while Troy Deeney punished a loose back-pass from Georginio Wijnaldum to give Watford a 1-0 home victory over Newcastle.- Morrison rescues West Brom -
West Brom manager Tony Pulis had James Morrison to thank for an equaliser in the fifth minute of stoppage time that prevented his side from losing at home to second-tier Bristol City.
After substitute Saido Berahino gave West Brom a 67th-minute lead, goals from Jonathan Kodjia and Kieran Agard put Bristol City in charge, only for Morrison to secure a 2-2 draw at the death.
Aston Villa's wretched season continued as they were taken to a replay by fourth-tier minnows Wycombe Wanderers following a 1-1 draw at Adams Park - their 16th successive game without victory.
Eleven points adrift of safety at the foot of the Premier League table, Villa took a 22nd-minute lead through Micah Richards, only for Joe Jacobsen to equalise with a penalty early in the second half.
Villa captain Richards went over to speak to frustrated Villa fans at the final whistle and manager Remi Garde said: "It was brave of him to do that.
"As professionals, we have to face our responsibilities - not only Micah, me and all the players."
Bolton Wanderers, bottom of the Championship and at risk of bankruptcy, narrowly escaped succumbing to the day's biggest shock as Darren Pratley's scrappy 87th-minute goal earned them a 1-1 draw at fifth-tier Eastleigh.
The lowest-ranked team left in the tournament, Eastleigh had gone ahead in the 51st minute via an own goal by Bolton's French defender Dorian Dervite.
Manchester United face lower-league opposition later on Saturday in the form of third-tier cup specialists Sheffield United, who reached the League Cup semi-finals last season and the FA Cup last four the year before.
Liverpool were taken to a replay by fourth-tier Exeter City on Friday, Brad Smith's 73rd-minute equaliser sparing Jurgen Klopp's youthful side from an ignominious exit.
3rd rd results
Arsenal 3 (Campbell 25, Ramsey 72, Giroud 75) Sunderland 1 (Lens 17)
Birmingham 1 (Morrison 40) Bournemouth 2 (Tomlin 44-pen, Murray 85)
Brentford 0 Walsall 1 (Mantom 34)
Bury 0 Bradford 0
Colchester 2 (Moncur 28, Sordell 41) Charlton 1 (Ghoochannejhad 90)
Doncaster 1 (Tyson 25) Stoke 2 (Crouch 15, Walters 57)
Eastleigh 1 (Dervite 51-og) Bolton 1 (Pratley 87)
Everton 2 (Kone 32, Mirallas 85-pen) Dagenham and Redbridge 0
Hartlepool 1 (Gray 61) Derby 2 (Butterfield 67, Bent 85)
Huddersfield 2 (Paterson 57, Wells 90+2-pen) Reading 2 (Vydra 71, Robson-Kanu 87)
Hull 1 (Snodgrass 41-pen) Brighton 0
Ipswich 2 (Oar 53, Fraser 88) Portsmouth 2 (Bennett 55, Chaplin 86)
Leeds 2 (Carayol 45, Doukara 90) Rotherham 0
Middlesbrough 1 (Fabbrini 36) Burnley 2 (Hennings 45+1, Ward 71)
Northampton 2 (Holmes 49, 58) Milton Keynes Dons 2 (Cresswell 13-og, Maynard 82)
Norwich 0 Manchester City 3 (Aguero 16, Iheanacho 31, De Bruyne 78)
Nottingham Forest 1 (Ward 24) QPR 0
Peterborough 2 (Samuelsen 7, Washington 52) Preston 0
Sheffield Wednesday 2 (Bannan 42, Nuhiu 73) Fulham 1 (Dembele 43)
Southampton 1 (Romeu 51) Crystal Palace 2 (Ward 29, Zaha 68)
Watford 1 (Deeney 44) Newcastle 0
West Brom 2 (Berahino 67, Morrison 90+5) Bristol City 2 (Kodjia 74, Agard 83)
West Ham 1 (Jelavic 85) Wolves 0
Wycombe 1 (Jacobson 50-pen) Aston Villa 1 (Richards 22)
Exeter 2 (Nichols 9, Holmes 45+1) Liverpool 2 (Sinclair 12, Smith 73)