Swansea provided the biggest shock of the FA Cup fourth round so far when they fought back from a goal down to knock First Division Preston out at the Vetch Field.
After a goalless first half Dickson Etuhu broke the deadlock for the Division One play-off hopefuls after 58 minutes and seemingly set the Lancastrians on their way to round five. But Andy Robinson levelled with 10 minutes to go and Lee Trundle two minutes later to spark celebrations in south Wales and seal a 2-1 win.
Arsenal avenged their midweek defeat by Middlesbrough with a comfortable 4-1 FA Cup fourth-round win a Highbury. Middlesbrough beat the Gunners 1-0 in London in the first leg of their Carling Cup semi-final on Tuesday but they fared worse today when Dennis Bergkamp struck after 19 minutes.
Joseph-Desire Job equalised four minutes later to keep Boro in the hunt but Freddie Ljungberg restored the Arsenal advantage. The game was effectively sealed when Ljungberg claimed his second after 68 minutes but there was time left for George Boateng to be sent off for two yellow cards and David Bentley to add a fourth.
Colchester threatened an upset after taking the lead against First Division Coventry at Highfield Road but had to be content with a replay after a 1-1 draw. The Second Division side scored after half an hour through a Dele Adebola own goal but parity was restored through a Julian Joachim strike three minutes later.
Matthew Taylor ended Scunthorpe's hopes of a Cup upset with a brace to see Portsmouth safely into round five after a 2-1 win. Taylor opened the scoring after 35 minutes before making the game safe 31 minutes later. Scunthorpe at least got on the scoresheet late in the game thanks to Andy Parton.
Birmingham made the perfect start to their clash with First Division strugglers Wimbledon when Bryan Hughes scored after just four minutes. But the expected goal rush failed to materialise and the Barclaycard Premiership side had to make do with a narrow 1-0 win.
Burnley's top-scorer Robbie Blake scored twice to send the Clarets into the fifth round following a comfortable 3-1 home win over Gillingham. Ian Moore struck first for Burnley after half an hour and Blake made it two three minutes later before making it safe after 64 minutes - Darius Henderson got the Gills' consolation.
In the other all First Division encounter, at Portman Road, Sunderland beat Ipswich 2-1. The Wearsiders took the lead through a Tommy Smith goal on the stroke of half-time and Julio Arca made it two after 68 minutes.
Martijn Reuser pulled a goal back with a minute remaining for Ipswich. The battle between two Second Division sides at Kenilworth Road was decided by a Mickey Mellon goal with nine minutes to go which sent Tranmere through at the expense of Luton.
In the lunchtime kick-off, Nationwide Conference side Scarborough produced heroics on their way to a 1-0 defeat by Chelsea at the McCain Stadium. John Terry scored for the Premiership title challengers after just nine minutes but Scarborough rallied and should have had a late penalty when William Gallas appeared to handle.