In meeting Wozniacki last year at a World Heavyweight Boxing match in Hamburg, McIlroy progressed to winning the U.S. Open and then taking the huge step to World No. 1 earlier this year.

Wozniacki was the women's World No. 1 but has dropped to World No. 7 competing this week at Wimbledon.

Their relationship has become one of the most talked about in professional spoke, and certainly more than the pairing of Australia's Adam Scott and Serbian stunner Ana Ivanovic.

Evert, who endured a stormy third marriage to former long-time World No. 1 Greg Norman, was asked about McIlroy and Wozniacki during this week's Wimbledon Championship where she is commentating for U.S. TV.

"When you are that young like Rory and Caroline, your career is right at your fingertip," said Evert.

"It's a choice you have to make."

Evert now aged 57 won 18 Grand Slam titles in her career and was World No. 1 for seven years including from 1974 to '78 and then from 1980 to '81.

She still holds the record for seven French Open wins and six U.S. Open successes.

And Evert holds the record in both men's and women's tennis of a Singles winning average of 90.05% with victory in 1309 matches and losing just 145.

However she's disappointed that the likes of Wozniacki simply don't ask the older players, like Evert, for advice. It's also the same scenario in professional golf.

"I'd love to talk to Caroline but the younger players don't really approach the older players for advice, and that's just too bad," said Evert.

"You are compromising because you're in a relationship and you want somebody to support you.

"When Rory goes to tennis tournaments it is taking a little bit from his game, and vice versa.

"I don't think Caroline's tennis is slipping because she is in love. When she racked up all those ranking points last year, Serena and Venus Williams were out of the game and Victoria Azarenka had not come on strong.

"There was an opening and Caroline was the most consistent player.

"Now all her ranking points are coming off but it is not because of her relationship. It's more that, as she lost her ranking points, three of four other girls have really got better.

"Caroline hasn't made the right adjustments to her game, like playing more aggressively and getting a bigger serve."