Rumours were rife again yesterday that the pair were set to tie the knot after tennis star Wozniacki was seen wearing a sparkling new diamond ring.
But McIlroy's spokeswoman bluntly denied in a short statement that they were about to take a trip down the aisle.
Just last month, Wozniacki took to Twitter to deny the Co Down golfer had popped the question after Serena Williams's practice partner Sascha Bajin jokingly tweeted congratulations to them.
Media outlets drew the wrong conclusion again this week when she was seen in Australia wearing what looked like an engagement ring.
The Danish tennis player wore the large sapphire and diamond ring on her left hand when arriving to play her first match in the Brisbane International competition.
She was later reported to have removed the ring before practising.
In a statement, McIlroy's spokeswoman said the pair were not engaged, as had been reported originally in the Australian press.
"Rory is in Australia to support Caroline before he heads in January to Abu Dhabi," she said.
The world's number one golfer and Wozniacki, previously world number one in her sport, have been dating since 2011.
Nicknamed Wozzilroy by McIlroy, the couple recently featured in Forbes magazine's influential list of 30 under 30.
In response to the rumours put out by Sascha Bajin last month, Caroline tweeted back: "Can't believe you started rumours like that! @BigSascha .. Not engaged yet, but you'll be the first to know if we do!) hehe."
Speaking at Brisbane Airport, Wozniacki said: "It's a new year and all I want to do is my best and we'll see what happens. Obviously I want to go far here.
"I've never been to Brisbane so I want to start off well and this field gives the perfect preparation."
Although they may not be contemplating marriage, the couple's relationship has taken a more serious turn after McIlroy bought a €8m luxury home in Florida recently.
He is expected to share the six-bedroom home, which is situated just a few miles from Tiger Woods's estate, with Wozniacki.
McIlroy, who earned €11,904,126 this year, recently put the home he shared with ex-girlfriend Holly Sweeney up for sale.
It is understood that two bids were being considered for the luxury €2m house outside Belfast.
One has been lodged by an international businessman and a second from a London-based bidder who wants to return home.
The sale is expected to go through early in the new year.