The 33-year-old Irvine, whose second place at Sunday's British Grand Prix left him level with the German in the standings, eight points behind McLaren-Mercedes' Mika Hakkinen, has been handed the task of delivering the Italian team their first drivers' title in 20 years.
A Ferrari spokesman said: "It will be several weeks, perhaps six to eight, before Michael will be fit enough to resume racing. Now Eddie will be our No 1 driver in the championship and he will have all the team effort and support that a No 1 driver has."
Ferrari hope to name Irvine's new team-mate today. Italy's Luca Badoer, the team's test driver, could be released from racing duties with Minardi Ford, while Finland's Mika Salo, a replacement driver at BAR, would also be available.
Another candidate is Sauber's Jean Alesi, unloaded by Ferrari to make way for Schumacher in 1996. The prospect of pairing the volatile French- Sicilian with the irreverent Irvine might prove too heady for some, but Jean Todt, the team's sporting director, has an open mind.
He said: "Jean Alesi is contracted to Sauber but he is still a possibility. We need someone who knows Ferrari and the car, someone who is friends with Ferrari."
Irvine will be more concerned with the opportunity suddenly presented to him. "The chance is there to go for the championship and that's what I want out of Formula One," he said. "But we need to improve the car. I'm driving out of my skin at the moment."
The Ulsterman has maintained all along that driving for Ferrari, even as No 2, is the best route to a tilt at the championship. During the build up to the British Grand Prix, he told the Independent: "I haven't stayed at Ferrari because I wanted to help Michael Schumacher win the world championship. I'm here because of me."
Irvine seemed to be aiming no higher than second best this year but he said: "You never know, it could be first. Michael might slip on a banana skin tomorrow. You don't wish bad luck on anyone but I'm out there for me. If he has a problem, I have to take advantage."
If that was eerily prophetic, the irony of another comment was positively spooky: "You always learn from Michael, especially on a circuit like Silverstone, the way he pushes through the fast corners. You know it's there to be done so you have to put your heart in your mouth and go for it."
Irvine believes his promotion will enhance his performance. "It always makes me feel stronger when the team are focusing on me. It makes me feel I've got to do the job because it's down to me."
However, Todt questions Irvine's temperament as he believes the tension of Sunday's race managed to get to him. "The championship will be tough to win for us. But we will give it everything and only time will tell what will happen," Todt said.
"I hope Irvine can win the drivers' title. Life has been such that he has often been behind Michael, but Michael will not be there for a few weeks so it's up to him to win as much as he can.
"He will be supported as he always has been. He has never been the second driver. It's the facts which have decided that Irvine is the second driver because Michael has always been faster than him. If he had been ahead of Michael then he would have been the first driver.
"Now he has a chance to win the championship - just like he had a chance to win yesterday's race. But he made a mistake [when he overshot his pit- stop mark]. Maybe he was nervous.
"But with Michael out it's the team I feel sorry for because we've so many good people working for us and we have such a good car. But that's motor sport. These things happen."