For the first of his brace in their Division 1 match, Geldhardt picked up the ball from 45 yards out and firing a left-foot shot beyond goalkeeper Marcelo Pitaluga.
The 19-year-old rifled in their fourth from distance and was only denied a hat-trick by a fine late penalty save from Pitaluga.
Mika Biereth netted a hat-trick and Folarin Balogun struck twice, before an own goal from Lewis Hall made it 6-0. Jayden Wareham pulled a late goal back.
The Gunners were also on form in a London derby victory at Under-18 level this weekend, with Charles Sagoe Jr scoring a brilliant winner to secure a 2-1 U18 Premier League Cup success at West Ham United.
We need to talk about this Charles Sagoe Jr winner 🤩— Arsenal Academy (@ArsenalAcademy) September 20, 2021
With the scores level in the 89th minute of our under-18s' Premier League Cup match at West Ham, Charles did THIS to give us the W 🙌 pic.twitter.com/vXkrdFBJkp
Anthony Elanga had fired the Red Devils ahead from the penalty spot before Swiss striker Lorent Tolaj levelled.
59: Huge moment this! 👇— Southampton FC (@SouthamptonFC) September 19, 2021
Ollie Wright guesses the right way to keep Saints B in the game! [0-1] pic.twitter.com/W49kaaVS9L
Blackburn 3-3 Spurs
Man City 4-2 Crystal Palace
Man Utd 2-1 Brighton
Chelsea 1-6 Arsenal
Liverpool 0-4 Leeds
Derby 3-1 West Ham
Leicester 3-1 Everton
Aston Villa 4-2 West Brom
Southampton 0-2 Burnley
Sunderland 1-3 Middlesbrough
Newcastle 2-3 Stoke
Nott'm Forest 5-0 Birmingham
Reading 3-3 Norwich
Wolves 2-1 Fulham
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