Ainsley Maitland-Niles got his first goal for the Gunners to give the visitors an early lead, but two goals from Roberto Firmino, one from Sadio Mane and a Mohamed Salah penalty gave Liverpool total control by half-time. Firmino completed the rout, and his hat-trick, with a second-half penalty.
Tottenham saw the gap to Premier League leaders Liverpool widen as Wolves fought back to defeat Mauricio Pochettino’s side.
Harry Kane’s stunning strike from range had given Spurs a first-half lead, but goals from Willy Boly, Raul Jimenez and Helder Costa turned the game around.
Meanwhile, there were two late winners at the opposite end of the table.
Aleksandar Mitrovic struck in stoppage time to earn Fulham victory over fellow strugglers Huddersfield, after team-mate Aboubakar Kamara had a penalty saved.
The win moves Fulham up to 18th but Huddersfield remain bottom, five points from safety.
And Victor Camarasa’s 92nd minute goal against Leicester earned Cardiff City their first away win of the season.
The result sees Neil Warnock’s side move up to 16th, four points clear of the bottom three.
Watford rescued a point against Newcastle at Vicarage Road courtesy of substitute Abdoulaye Doucoure’s equaliser eight minutes from time.