In 1997 Downing, then 12, was one of the Middlesbrough schoolboys who went to Wembley full of hope for his home-town club's first FA Cup final.
But within 42 seconds Chelsea were ahead thanks to Di Matteo's 25-yard thunderbolt.
Liverpool star Downing said: "We all remember Di Matteo's goal so early, going in off the bar. I've hated him ever since! What did I call him? Nothing I could repeat. But he was a good player and has done well as manager at Chelsea."