Samoa led England at half-time in their pool clash and a 12-year-old Tuilagi, the youngest member of a rugby dynasty, was roaring on his countrymen.
The following year, Tuilagi made the life-changing move to join his brothers - four of whom are Samoa internationals - and live in Leicester.
After one sensational season with the Tigers, Tuilagi is now preparing to represent his adopted country at the World Cup after being named in England's final 30-man squad.
"I've never been to a World Cup before. I watched that game against England in 2003. I was in Samoa - cheering for Samoa!" said Tuilagi.
"Before the start of last season my target was just to get into the Leicester first team. I didn't really think I would have a chance with England until I got called into the training squad.
"I got a phone call last Monday and I just couldn't believe it, I was in the final squad.
"I rang my family straight away, back in Samoa. They were asleep at the time - it was four o'clock in the morning there, but they were very happy for me.
"They will definitely come over to watch me, because it's not far from Samoa to New Zealand.
"There will be a lot of Tuilagis out there - seven or eight, maybe even 10! I'm going to have to buy a lot of tickets."
Tuilagi made a try-scoring Test debut in England's victory over Wales at Twickenham earlier this month and he is pushing for a second start against Ireland in Dublin on Saturday.
England manager Martin Johnson will confirm his line-up tomorrow but Tuilagi, although normally considered an outside centre, could emerge as an option for England in the 12 jersey.
Shontayne Hape is the only specialist inside centre in England's final 30-man squad.
Tuilagi is as strong as England's props and his work ethic has impressed Johnson and the whole red rose management.
"I want to get a start," said Tuilagi.
"I just run hard at defenders and try to break them down. It is simple but it's effective really.
"I just have to keep training hard and hopefully get picked."
England were on Wednesday waiting on the results of a scan on James Haskell's foot but the management did not suspect it to be anything serious.
Scrum coach Graham Rowntree described it as a "minor foot injury".
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