American teenager Michelle Wie could become the first woman to play in The Open at St Andrews later this year.
Wie could gain qualification at the John Deere Classic
Organisers have agreed for the first time to allow women to enter if they qualify through the normal channels.
The ruling opens the door for the 15-year-old, the only female golfer who has so far targeted an Open place.
She has accepted an invitation to play at July's John Deere Classic, which gives an Open place to the leading player who hasn't already qualified.
Until Tuesday's ruling, the Royal & Ancient Golf Club would have been forced to refuse Wie entry even in the unlikely event she had won the John Deere Classic because it has a "men-only" restriction on the Open entry form.
The R&A has already voted to remove it in time for next year's tournament at Hoylake near Liverpool although it was too late to remove the restriction for this year's event.
But on Tuesday officials said they would waive it if the Hawaiian youngster qualified.
"If Michelle Wie wins the John Deere Classic, she would qualify for the Open championship," R&A chief executive Peter Dawson told a news conference at St Andrews.
"There is a clause in the entry form for this year's tournament about the championship committee having the discretion to accept or refuse any entry."
BBC Radio Five Live reporter Andrew Cotter, who was at St Andrews, said Wie needs to finish in the top ten in the John Deere Classic, which takes place in Illinois a week before the Open, to have a chance of qualifying.
"If she was to become the leading player there not already qualified for the Open, which might mean something like a fifth or tenth-place finish, she would be playing in the Open this year."
Even a top ten finish would seem highly unlikely, with Wie - who is still an amateur - failing to make the cut for the final stages of the men's events she has entered to date.
Cotter said the R&A said it had not yet had any Open entries from women for this year but would take each case on its merit.
Dawson added: "There is no resistance to women playing in the Open championship if they can qualify for the championship.
"The hesitancy is in the detail, not in the principle.
"For example, a scratch woman amateur does not play off the same tees as a scratch male amateur," he said.
"It's new ground in sport as a whole.
"The only Olympic sport where the two sexes compete together is equestrianism and it is not surprising therefore it is taking a long time.
"We've not asked players their views. We are not in the habit of taking polls, but we keep our ears to the ground. There won't be a complete consensus on this.
"I've consulted with the tours on this matter and I can't say I have met any resistance to it."
Women have already taken on the men.
Two years ago, world number one Annika Sorenstam became the first female to appear on the US Tour since 1945.
Britain's Laura Davies has also played in a tournament in Australia co-sanctioned by the European and Australasian tours while Wie, then 14, missed the cut by only one stroke at last year's Sony Open.
Former European tour executive director Ken Schofield let it be known before his retirement last year that he hoped Davies' appearance on the circuit was a one-off.
But Martin Kippax, chairman of the Royal and Ancient Club's championship committee, insisted Schofield's view was not shared by the majority.
"We are not resentful - there is no resistance to it here. It's novel and something that is new needs to be considered," he said.
"We are not dragging our feet in any way. We are giving it the consideration it deserves because there needs to be a level playing field. We are perfectly happy about it."
The Open Championship starts on 14 July.