Fahey will meet with Brian Cookson, the new president of cycling governing body UCI, on Wednesday to discuss the fallout from the Lance Armstrong scandal.
The outgoing WADA chief said it would take "something close to a miracle" for Armstrong's life ban to be reduced in return for co-operating with the investigation.
"There'd have to be a damn good reason," Fahey said.
WADA has also received the report into the breakdown of drug testing procedures in Jamaica ahead of last year's London Olympics and will examine that "quite extensive" document in detail at the end of this week's World Conference on Doping in Sport, according to Fahey, after Jamaican authorities are given a chance to respond to it. They have until the end of the week.
"They dropped the ball. It's clear," Fahey said of Jamaica's anti-doping controls.
Fahey said it is "almost certain" that the doping laboratory in Brazil which had its WADA accreditation revoked would not be ready in time for next year's World Cup. As a result, FIFA announced that it had reached a deal to fly the hundreds of player samples before and during the football showpiece from Brazil to a WADA-accredited lab in Lausanne, Switzerland.
Fahey also used Tuesday's news conference to announce a new "steroid module" that will come into use in 2014. The new technology will mirror the biological passport that currently tracks athletes' blood profile and will help detect steroid use and particularly testosterone, Fahey said.
He said the steroid module is "ready to run" and FIFA said it would use it at the World Cup, one of the first federations to implement the procedure.
Fahey promised progress on cycling's future and Jamaica at the four-day summit in Johannesburg, which opened on Tuesday and will be the last major task for the former Australian politician as president of the anti-doping body.
The main business for this week's meeting is to review and update the World Anti-Doping Code and elect a new president of WADA. IOC vice-president Craig Reedie from Britain is the only candidate in Friday's election to succeed Fahey. He will take over on Jan. 1.
Four-year bans for intentional dopers, more emphasis on investigations to catch cheats and strengthening punishments for coaches and officials who help athletes dope are expected to be adopted and added to the code on Friday when WADA votes on the proposals. The new code will come into effect on Jan. 1, 2015, in time for the 2016 Olympics in Rio de Janeiro.
Cycling and concerns over Jamaica could dominate the behind-the-scenes discussions in Johannesburg.
That will start with Wednesday's meeting between WADA and Cookson, who made contact with the agency almost as soon as he was elected in September, Fahey said. An independent commission to investigate and shed light on cycling's dark doping history is now imminent.
"I am confident that from what UCI have indicated, and their wish to get something going, that it will happen within weeks rather than within months," Fahey said. "The goodwill appears to be there. The utmost co-operation will be given by us. Hopefully, we'll make a further step down that path of some significance in our discussions tomorrow."
However, Fahey said there would have to be "extraordinarily powerful reasons" for Armstrong, who was banned for life and stripped of his seven Tour de France titles last year, to have his case re-opened and his ban reduced for co-operating with the commission. Armstrong's intention to seek a reduction in his ban from all organized sport has been the subject of major speculation with the disgraced American rider intimating in interviews that he would be willing to co-operate in return for leniency.
"As far as I'm concerned it's (Armstrong's case) done and dusted," Fahey said. "Armstrong did what he did. We all know what that is. He did not co-operate, he did not defend the charges that USADA put out there last year and he was dealt with in a proper process."
Fahey said the United States Anti-Doping Agency case against Armstrong and his eventual life ban were "irrefutable" and repeated the standpoint of USDADA chief executive Travis Tygart, who has questioned the "value" of Armstrong's testimony over a year after the case was brought against him.
For Jamaica, WADA has given the country's sports minister and the Jamaican Anti-Doping Commission until the end of this week to respond to the report before it is examined at WADA's foundation board meeting on Friday and any findings are announced.
"That report, which is quite extensive, contains a number of key recommendations," Fahey said. "They deal with the governance, they deal with the operations, and sometimes they overlap between the governance and the operations which we don't think works very well."
Jamaica is reportedly sending a delegation to Johannesburg to attend the conference.
There was little progress, however, on Kenya after allegations of widespread doping in that country and a recent spike in positive tests for its athletes. Fahey and WADA director general David Howman said they had heard nothing after reports that the Kenyan government had finally made progress on setting up an investigation — over a year after they promised to.
Follow Gerald Imray at www.twitter.com/GeraldImrayAP