The then 20-year-old suffered a season-ending foot injury in a Premier League for Manchester United against Chelsea two months before the start of the tournament in Germany.
Rooney was deemed doubtful for the tournament but made a quicker-than-expected recovery to be named in Sven-Goran Eriksson’s 23-man squad.
Rooney was England’s biggest hope going into the tournament, having exploded onto the scene as an 18-year-old with four goals at EURO 2004.
In Germany, Rooney’s injury problems were evidently not behind him as he made four scoreless appearances before getting sent off against Portugal in the quarterfinal.
The 34-year-old, who now plays for Derby County in the second tier of English football, says he aggravated the injury during training at the Mundial, and should not have gone in the first place.
He told the Sunday Times: "I hit it [the ball] from the halfway line, trying to strike the crossbar and felt my groin tear. I knew straight away.
"I got one of the physios to work quietly on it every day. I was taking painkillers. I didn't want to say anything because a lot of people had put a lot of work into getting me fit.
"I didn't report the injury until the tournament was over and there was a 6cm tear in my groin."
"Looking back, I should never have gone to that World Cup.
"If the Euros were going ahead this summer, I'd have said to Harry Kane and Marcus Rashford that if they were struggling in any way, not to push it.
"Of course it's hindsight. Back then I was 20, it was my first World Cup and there was so much expectation on me."
