Mirjana Lucic was four years old when she hid on the back seat of the family car as her father took her older sister, Ana, for a tennis lesson at a local club in the Croatian seaside town of Makarska. Mirjana sneaked on the court. "When I took the racket, I wouldn't let it go," she said.
Her grip has been loosened from time to time by the WTA Tour's age eligibility rule, which restricts the number of tournaments accessible to players under 18. Having marked her 16th birthday yesterday, Lucic is entitled to increase her activity from eight to 10 WTA Tour events (starting with the Lipton Championships in Florida on 19 March), plus the year-end championships and any of the four Grand Slam tournaments for which she gains direct entry by virtue of her world ranking. At the age of 17, she will be eligible to play 13 WTA Tour events.
Lucic's father, Marinko, a former Olympic decathlete, considers that his daughter has been penalised by the rule. He was particularly upset when Mirjana was not given wild cards for the French Open (won by her compatriot, Iva Majoli, 19) and Wimbledon (won by Hingis, 16).
If time has been allowed to pass his daughter by, it has done so fleetingly. The latest addition to the WTA Tour's attractive and varied cast of teenagers - Hingis, with the big smile and stunningly mature game, Anna Kournikova, every ball-boy's dream, and the Williams sisters, Venus and Serena, winning with attitude - Lucic is accustomed to appraisal. Almost 6ft tall, blonde, blessed with an aggressive baseline game and the strength and timing to serve consistently in excess of 100 mph, she commands attention.
Her arrival on the WTA Tour was spectacular. Unranked, and a qualifier, she became the first player ever to win a professional tournament on her debut, appropriately at the Croatian Open last May. Lucic did not drop a set, and in the semi-finals defeated Amanda Coetzer, the diminutive South African who had eliminated Steffi Graf at the 1997 Australian Open and was soon to beat the German again at the French Open. "Mirjana is an incredible girl," Coetzer said. "She beat me in everything I was trying."
In her second event on the major tour, in mid-May, still unranked and having qualified for the main draw in Strasbourg, Lucic defeated two seeds, Judith Wiesner and Nathalie Tauziat, before losing to Graf, her idol, in the final, 6-2, 7-5. Afterwards, Graf told Lucic she had a great future and informed reporters, "I was not nearly as good as she is at 15".
Graf, who joined the tour at the age of 13 after outclassing the junior competition, graduated steadily through the senior ranks, by current standards, moving into the world's top 10 during her third season. It was the American Jennifer Capriati's prodigious leap from the juniors to a Grand Slam semi- final at 14, and her subsequent emotional turmoil, that prompted the tennis administrators to address age eligibility.
On 1 July, having competed in her third professional tournament, advancing to the final of a satellite event in Marseilles, Lucic qualified for a world ranking, No 69. That persuaded the United States Tennis Association to accept her entry for the US Open singles draw of 128.
Confident of performing well when able to trust the even bounce of the balls on medium-pace concrete (she won the 1996 US Open junior singles championship and the 1997 Australian Open junior singles and doubles titles), Lucic marked her Grand Slam debut by advancing to the third round at Flushing Meadow, elevating her ranking to No 50. She was defeated in three sets by Jana Novotna, the No 3 seed, who concluded that, "Lucic hits the ball harder than anyone."
Last May, Lucic received an invitation to Switzerland the moment Hingis was fit to practise after surgery to repair a knee damaged in a fall from a horse. It was not the first time that the young Croat had visited Trubbach to play with Hingis on the rubberised concrete court at the world No 1's home (the "Rebound Ace" is a replica of the surface at the Australian Open). The youngsters became friends after meeting at the Fed Cup in Spain in April 1996, and Lucic is valued both as a companion and a powerful sparring partner.
In Novotna's absence at the Australian Open two months ago, Hingis invited Lucic to partner her in the doubles. They won the title, a victory which made amends for Lucic's second-round defeat in the singles by Majoli, the No 4 seed.
"Tennis-wise, Mirjana is one of the biggest threats to Martina," said Melanie Molitor, Hingis' mother and coach, qualifying the compliment, perhaps with a future rivalry in mind, by adding, "but maybe not mentally."
Marinko Lucic, who has four other children, resents any suggestion that he is an opportunist, having sold a restaurant and three grocery stores in order to concentrate on supervising Mirjana's career. "She'll be No 1 in the world some day, if God allows it, but we've learned from the mistakes of the others," he told the New York Times.
"They looked too much at the money. Yes, it's a business, but the focus should be on the game, and the money will come later if you do this correctly. I wish that my daughter doesn't play past 25. I want her to get friends, get married, and have a life. We don't want to lose perspective." Amen to that.