A survey of ticket categories on sale has shown that the tournament is selling out in the cheap seats.
In most venues - particularly Eden Park - the expensive seats have remained plentiful as the cheaper seats sold out.
Tournament organisers yesterday did not say how many tickets were being upgraded, or whetherthe changes were confined to Eden Park.
Spokesman Mike Jaspers said only that "fine-tuning" had been required as camera positions and temporary seating were finalised.
"The requirements for Rugby World Cup 2011 are significantly larger than a normal rugby test, so some fine-tuning is inevitably required.
"This has affected a small number of seats and those fans have been compensated for any inconvenience with a better seating option."
The number of sold-out matches has fallen from four to just two.
France-Canada and South Africa-Samoa have both lost their "allocation exhausted" status, leaving only the finals and the NZ-France game sold out.
Many seating categories, including Categories A and C to semifinal number two - likely to feature the All Blacks - became available again this week.
Tournament organisers said more tickets had been made available to the public after the rugby boards, sponsors and travel agents did not want them.
Organisers have so far sold one million of the 1.6 million tickets, or three-quarters of their target of 1.35 million.
They had previously said that they would not discount ticket prices under any circumstances.