Griggs was on fire against West Ham - netting twice to eliminate the Premier League team
League One leaders Wigan knocked Premier League West Ham out of the FA Cup on an afternoon that saw the Hammers' Arthur Masuaku dismissed for spitting at Wigan's Nick Powell.
Northern Ireland international Will Griggs scored twice, making him the leading scorer in the competition this season with six goals in five games.
Veteran striker Jon Stead struck an equaliser for League Two Notts County at home to Swansea as the Magpies took the Premier League club to a replay after a 1-1 draw.
The Swans had been the better side in the opening half and led after Luciano Narsingh struck just before the interval but Kevin Nolan's side were much improved after the break.
Match report: Wigan 2-0 West Ham
Match report: Notts County 1-1 Swansea
It is not just Swansea who face a replay against lower-division opposition.
Huddersfield took the lead against Championship Birmingham through Steve Mounie but Lukas Jutkiewicz equalised after the break.
It looked to be heading for a draw at the Riverside too in the match between Middlesbrough and Brighton, but Glenn Murray's eventful week ended with a late winner for the Seagulls.
Match report: Huddersfield 1-1 Birmingham
Match report: Middlesbrough 0-1 Brighton
In the only all-Premier League tie among the nine matches at 15:00 GMT, new Watford manager Javi Gracia got off to a losing start with a 1-0 defeat at Southampton.
The only goal of the game came from defender Jack Stephens after just four minutes, while Saints new £19m signing Guido Carrillo made his debut as a second-half substitute.
Match report: Southampton 1-0 Watford
Coventry's fine FA Cup run continued.
The Sky Blues knocked out Stoke in the previous round - with Potters boss Mark Hughes sacked hours afterwards - and the League Two side won at MK Dons on Saturday with Maxime Biamou scoring the only goal.
But there was frustration for League One strugglers Rochdale, who led 2-1 at Championship Millwall until Ben Thompson struck a late equaliser as the match finished 2-2.
Match report: MK Dons 0-1 Coventry
Match report: Millwall 2-2 Rochdale
Hull knocked out Championship rivals Nottingham Forest, with Jarrod Bowen and Nouha Dicko scoring first-half goals. Apostolos Vellios pulled a goal back for Forest close to full-time but they could not find an equaliser.
In Saturday's other all-Championship tie, Sheffield United striker Billy Sharp scored a second-half penalty as the Blades knocked out Preston.
Match report: Hull 2-1 Forest
Match report: Sheffield United 1-0 Preston
Earlier on Saturday, there were no problems for Premier League Leicester, who scored five at Peterborough with new signing Fousseni Diabate notching twice on his debut.
Match report: Peterborough 1-5 Leicester
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FA Cup: Peterborough United 1-5 Leicester City highlights
The two fixtures still to take place on Saturday sees Welsh side Newport host Spurs before the all-Premier League tie between Liverpool and West Brom at Anfield.
Match preview: Newport v Tottenham
Match preview: Liverpool v West Brom
On Friday evening, Alexis Sanchez made his Manchester United debut in a 4-0 win at Yeovil. The Chilean played for 72 minutes and laid on two assists.
Match report: Yeovil 0-4 Manchester United
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Source: bbc.com