League One side Gillingham produced the biggest shock in Saturday's FA Cup third round as they beat Premier League Cardiff City, while Championship Bristol City knocked out the top flight's bottom club Huddersfield Town.
Holders Chelsea, record 13-time winners Arsenal and Manchester United were among the sides to make it through to Monday's fourth-round draw.
Two Championship teams suffered defeats at the hands of opponents from lower divisions, with Norwich beaten 1-0 at home by Andre Green's late goal for Portsmouth and Accrington overcoming Ipswich 1-0 through Billy Kee's strike.
Elliott List was the hero with an 81st-minute winner as Gillingham, 19th in the third tier, beat the 2008 finalists Cardiff, 17th in the Premier League table.
Huddersfield were knocked out by Josh Brownhill's 72nd-minute winner as Bristol City, who reached the semi-finals of the League Cup last season, made it through.
Elliott List scores to help League One side Gillingham eliminate Cardiff from the FA Cup
Alvaro Morata scored twice as Chelsea beat Championship side Nottingham Forest 2-0, but Cesc Fabregas, who is reported to be joining Monaco in the January transfer window, missed a first-half penalty.
There was no upset at Bloomfield Road, where Arsenal overcame League One Blackpool 3-0, with two goals scored from 19-year-old Joe Willock and another by Alex Iwobi.
The attendance of 8,995 - including 5,218 Gunners fans - was well below capacity as home supporters stayed away in protest against club owner Owen Oyston.
A penalty by Juan Mata - awarded after consulting the video assistant referee - and Romelu Lukaku's third goal in as many games proved enough for Manchester United as they beat their Championship Reading 2-0 at Old Trafford.
Gillingham 1-0 Cardiff
Bristol City 1-0 Huddersfield
Accrington Stanley 1-0 Ipswich Town
Norwich 0-1 Portsmouth
Chelsea 2-0 Nottingham Forest
Blackpool 0-3 Arsenal
Manchester United 2-0 Reading
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