This is from page 167 ff of Anders Haahr Rasmussen's 2010 book "Én bold ad gangen: Wozniacki, US Open 2009". This is my translation. Any errors are mine or the magic elves'.
Piotr Wozniacki has always been on the sideline when his doughter has played tennis.He can count three tournaments since 1997 where she's played without him.
There are many stories about him, like how, in the early years, he'd walk on court and interfere during her practices, so much so that her coaches would ask him to stand on the other side of the fence. Or how he still participates actively in the national team's strategy meetings (while she was still playing Fed Cup: Manixdk). Or how, if Caroline Wozniacki asks for pasta, for example, in a restaurant, he can cancel the order and insist she eat chicken instead.
There's a widespread scepticism about fathers in women's tennis, and not without some basis in fact. The first rumours about a dominating father stem from way back in 1910s and 1920s, when the very fashion conscious (and brandy drinking during matches) Suzanne Langlen, La Divine, won everything, (footnote: "won everything" means almost literally everything. Between 1919 to 1926 she lost only one match, and that was at the US championships when, coughing and crying, she had to pull out of her match against Molly Mallory because of illness) and drew hordes of photographers, and her father, where ever she went.
Charles Langlen, a failed competitive cyclist, was known to scold his daughter severely in public if she didn't play her best, and not allow jam on her bread if she had a bad practise session. (footnote: food seems to be a theme in these father-daughter relationships. Yanina Wickmayer's father was heard to say in the players' restaurant: "See what those girls are eating! That's why they get so fat and never win anything.")
Jim Pierce, father and coach of one of the biggest teenage talents, Mary Pierce, took it one step further. When she was only 10 years old, he wrote in his notebook what her goal was: "She'll be number one. She will dominate." After years of hitting her after she lost -- he once threw a racquet bag at her while she was on her way from the court after a loss to an unseeded player at an Italian tournament before he slapped her in the parking lot -- and drawing attention to himself in the crowd with shouts like "Go on Mary, kill the bitch!",
Jim Pierce had a police restraining order slapped on him at his daughter's request. Mary had begun to travel incognito with body guards. He managed to attack several spectators before the WTA denied him access to her matches. (Footnote: The 1990s delivered enough raw drama for several Hollywood films. Like the case of Mirjana Lucic, the world's number one junior player and the youngest winner of a Grand Slam trophy when she won the Junior Australian Open doubles title at 15 in 1998, the same year she fled Croatia in the middle of the night with her mother and four siblings to get away from her father, who beat her regularly with his heavy Timberland boots. Lucic received political asylum in the US, and said later that she had been diagnosed with Post Traumatic Stress Syndrome. She said: "I never went to bed without saying a prayer, in my whole life, never. And I never got up in the morning without saying a prayer. And my prayer was always to get away from my father.")
There is absolutely no doubt that Piotr Wozniacki is unusually engaged in his daughter's tennis. He's spent thousands of hours with her on the court and spent hundreds of thousands of Danish kroner on travelling with her around the world. I have no idea why.
His story fits perfectly into the narrative of the father who fulfils his own frustrated career through his daughter.
A declining football/soccer career brought Piotr and his wife, Anna Wozniacki, to Odense, Denmark, to play for B1909 in 1985. His career was never a great success, and knee problems stopped it at the end of the 80s.
Now he's involved in his daughter's career "110 per cent" as he puts it. He willingly admits that he pushes her, that he's never satisfied, and neither should she be, because even if things seem to be going well, they can always be better.
It likely sounds unhealthy, over ambitious and a recipe for a serious family tragedy. I would be reticent to recommend it as a way to raise a daughter or develop a talent, unless you're ready to mentally break nine out ten of your guinea pigs.
But, in the case of Caroline Wozniacki, it seems to work. And I'm not just thinking of her smiling nature and obvious joy in playing, which are hard to ignore in the "father pushes daughter" analysis.
No, it's the power relationship that muddies things a bit. I don't know how loud the shouting is in the dressing room or hotel room, but the only time I heard a raised voice was in this tournament's (US Open 2009: Manixdk) first week, when Caroline Wozniacki was standing chatting with a few journalists.
Her dad walked by in a good mood and fired off a cheeky comment, which, unfortunately, I didn't catch, but caused Caroline to tell him off immediately in Polish.
There are the stories of little Caroline, who keeps on hitting the ball into the hockey goals, and who comes into the bedroom on a Sunday morning and shakes her father awake, because they've agreed to go running, and who won't take no for an answer when he looks out the window at the pouring rain and suggests they sleep for another hour.