The Fijians face the hosts in the tournament's first game in front of some 80,000 fans at Twickenham and Lomu says the English will need to be on their guard.
"Everyone is talking about the usual suspects in terms of who are going to win the tournament; the New Zealands, the Englands, the Irelands, the Wales," Lomu said.
"The problem is they forget about the Polynesian South Pacific Island boys and those guys have a game or two that they will upset a team somewhere along the line.
"In 2011 it was Tonga upsetting France and in 1991 it was Samoa upsetting Wales so this is what rugby brings... you never know what will happen in 80 minutes and whoever you think might win might not, so get out there and support your team."
Lomu is widely acknowledged as the first global superstar of the sport.
He shot to prominence at the 1995 World Cup in South Africa, scoring four tries in the All Blacks' 45–29 defeat of England, including one in which he ran straight over the top of fullback Mike Catt.
Although he never won a World Cup, Lomu remains the competition's leading try scorer with 15.
The Fijians must hope, however, for a below-par England.
"They (Fiji) have got the team to be able do it, it's just putting it on the park and hoping that the other team doesn't play as well," the 40-year-old Lomu said.
"So that's what they'll be hoping for, but in saying that though, England at home at Twickenham with the support that they have... mate that's going to be a formidable team to try to beat."
(Writing by Ossian Shine; Editing by Ed Osmond)
