Tiger Woods, winner of the last three major championships and four of the last five, has signed the richest endorsement contract in the history of sport - for $100 million.

That is what it has cost Nike to retain his services to September 2006, and yesterday the president of Nike Golf, Bob Wood, said: "We are really, really happy. We have a comprehensive agreement that covers Tiger from head to toe, plus using our golf ball."

The contract is said by the American magazine Golfweek to be "far beyond anything Michael Jordan received". Quoting a scource close to Nike, it went on: "This is absolutely the richest-ever sporting endorsement. Nothing has ever been close."

Not that it unduly impresses Earl Woods, Tiger's father. When his son turned professional in August 1996 the golfing world gasped when Nike paid $40m for his signature. But Earl, with an eye to the future, described that sum as being only "chump change" and yesterday he was similarly guarded.

"The next contract," he said, "in 2006 will make that $100 million look like a bargain. There's no doubt that Tiger is going to get better, he's far from having reached his potential. This deal reflects the growing stature of Tiger in world sports, and that is just going to continue to grow."

Woods has already won nine tournaments on the US Tour this year, the first to reach that mark since Sam Snead won 11 in 1950, and at St Andrews this year he became the youngest man ever to win a career grand slam when he won the Open by eight shots.

Prior to that he had won the 2000 US Open by 15 shots, and his first major championship, the US Masters in 1997, was won by 12 shots. Only in the US PGA of 1999, when he was chased to the line by Sergio Garcia before winning by one shot, was the slam in any danger.

He has ruled world golf in the past two years and, as Nike has discovered, such brilliance has its price. There is even scope for extending that contract because Nike, as of now, does not make golf clubs, and so that aspect of the Woods career is not covered by the current agreement. But it is anticipated that they will start, and when they do it will doubtless cost them yet more millions.

The scale of the new contract is bad news for the television companies in America who will shortly have to renegotiate their contract to cover the US Tour. The Tour organisers will be sure to capitalise on the fact that ratings soar whenever Tiger is anywhere near contention and will demand yet another huge increase, so enabling prize funds to go up yet again.

That in turn could be bad news for the European Tour which is already losing many of its best players to America, after the last round of TV talks produced purses of between £3m and £5m sterling for many events in the US.

If that figure were to rise substantially yet again then even players like Lee Westwood, Darren Clarke and Colin Montgomerie might be tempted to play more in the States, diminishing the attraction of European events.