Welcome back, King Henry!
The former France international, 34, left the Gunners in June 2007 as the club's record goal-scorer and returned last week on a two-month loan from New York Red Bulls.
He could hardly have made a more impressive comeback, showing his colleagues how to finish after Leeds, currently eighth in the Championship, held out stubbornly until the 79th minute, 11 minutes after Henry had come on to a rapturous welcome from the home fans.
It was his 227th Gunners goal and Arsenal's reward is a fourth round tie at home to Aston Villa.
After the match he told ESPN: "It's kind of weird, I only came back from holiday in Mexico 15 days ago, I never thought I was going to be playing for Arsenal again and then score the winner.
"The feeling I had when I scored was amazing, I've rejoined the club as a fan, I just wanted to come and help the team, and then I end up as man of the match - it wasn't my plan to be a hero.
"I'll always remember tonight. When it comes to Arsenal, something happens to me."
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