Industry experts believe the Nike deal will be worth around €20m a year -- over €50,000 a day -- to world number one McIlroy.
The deal propels McIlroy into Europe's top five sports stars in terms of sponsorship income, behind a couple of Formula One drivers, plus footballers Cristiano Ronaldo and Lionel Messi.
The huge sum is about half the sum Woods commanded at his peak and about the same level as he is on now.
Nike looks to be hedging its bets to an extent. The company now has the most recognisable face in golf in Woods, and the young pretender to his throne in McIlroy.
But are two personal endorsements to the tune of €40m a year really good value to Nike?
Tim Crow, chief executive of the London sponsorship agency Synergy, believes the answer is yes.
"Before Tiger Woods first signed, Nike were banking around 1pc of the golf equipment market worldwide, five years later it was 15pc," Mr Crow said. "Tiger did that for them.
"Signing McIlroy may well signal the changing of the guard, but Nike will now have the most high-profile guy in golf and the coming man. It's a win-win situation."
McIlroy is believed to have been testing Nike's clubs for the past two months and has already recorded his first TV ad with Woods.
In the ad, the two golfers engage in 'trash talk' as they hit more and more outrageous shots on the practice ground.
Woods, of course, has hardly been the advertiser's dream since his fall from grace after a much-publicised marriage break-up, and Mr Crow said any sponsor will factor in such a risk and should plan for the sort of worst-case scenario that Lance Armstrong's backers are facing now.
"Any savvy sponsor knows there is an element of risk and this is one of the key things we do with our clients," Mr Crow added.
"It's very important to ensure you have the right clauses in your contract and the right of recourse.
"I imagine a lot of guys involved with Lance Armstrong are looking to see what recourse they have got."
Mr Crow believes it is McIlroy's youth and refreshing approach to golf which make him such an attractive proposition.
"Youth is important but it's the whole package.
"He has a kind of old-fashioned naivety, a sheer joy in the game that contrasts with the manufactured personalities that you can sometimes appear to get with sports people."
The only possible cloud on the horizon is in relation to the Olympics in 2016, as McIlroy has said he may not play in order to avoid the tricky decision about whether to play for the Republic or Great Britain.
However, Mr Crow believes that issue will not be keeping anyone at Nike awake at nights, and that the company's bosses will just be happy to have got their man -- and he is Rory McIlroy.
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