The German forward left the Gunners in 2016 to join Bundesliga outfit Werder Bremen after making 18 appearances, but signed for Bayern just 12 months later after an impressive campaign in Germany.
The 24-year-old has risen to prominence at the Allianz Arena – locking down a regular spot in the national team – and returned to north London with a magnificent performance as the Bavarian giants roared to a memorable victory over Mauricio Pochettino’s side.
Gnabry wreaked havoc down the left against Serge Aurier and after the game, scoring a range of superb goals, and BT Sport pundit Ferdinand heaped praise on the winger.
“We spoke about [Robert] Lewandowski being the danger man,” the former Manchester United defender said.
“Today, Serge Gnabry, he showed Arsenal what they let go.”
The evening had begun well for Tottenham with Heung-min Son scoring in the 12th minute but Joshua Kimmich’s superb effort levelled things up in a rip-roaring start.
Lewandowski gave the visitors the lead on the stroke of half time and Gnabry piled on the misery for the hosts with a sizzling solo effort in the 53rd minute before slotting in his second shortly afterwards.
Harry Kane’s penalty restored some hope for Spurs on the hour but Bayern soon moved up a gear, with Gnabry completing his hat-trick seven minutes from time to make it 5-2.
Lewandowski then got his second and Gnabry struck a late fourth to add to Tottenham’s woes.