World number one Wozniacki, who has won 18 career titles including six this season but is still seeking her maiden grand slam victory, had the ear of the 29-year-old, 13-time major winner, but might have wasted the opportunity.

The 21-year-old Dane, who is dating US Open golf champion Rory McIlroy of Northern Ireland, asked Williams about her love life.

“I hope she didn’t listen,” Williams admitted to reporters after her second-round Open win Thursday.

“I told her never look through the guy’s phone. That is the worst thing you can do. I told her most relationships end.

“It wasn’t very good advice.” 

Wozniacki, who walloped unseeded Arantxa Rus of the Netherlands 6-2 6-0 to advance to the third round, said it was all in good fun.

“Well, we were all in the locker room,” Wozniacki explained. “I was going to get some treatment. She (Serena) was sitting there with Venus and talking.

“And then, I don’t know, it just came out that we were talking a bit and we had a laugh. We were just kidding around a little bit.” 

McIlroy, apparently, can breathe easy.

“Yeah, I think I should not listen to her or Venus,” the Dane said. “She (Venus) was not better.”