If she is to ever be taken seriously as a force in the game, Caroline Wozniacki needs to show more of the mongrel that briefly emerged during the third set of her loss to Svetlana Kuznetsova at the Australian Open when a call unfairly went against her.
Since reaching the final of the US Open more than three years ago, when she lost in straight sets to Kim Clijsters, Wozniacki has spent time ranked number one and been to the semis twice more at Flushing Meadows as well as at Melbourne Park and a quarter-final at the French Open.
But far too often the 22-year-old Dane, who is the glamorous half of one of world sport's current power couples with golf's world number one Rory McIlroy, fails to show any killer instinct on the court.
And it is that inability to put her foot on an opponent's throat when things are going her way that has so far proved the difference between reaching the top of the rankings as she makes the last four or eight at the grand slams and breaking through for a major victory.
In the deciding third set on Monday, Kuznetsova served wide to Wozniacki's forehand and a fault was called just as the 10th seed swung at the ball.
Kuznetsova challenged the call and after Hawk-Eye indicated that the tiniest part of the ball had caught the line, Wozniacki was left bewildered and angered that the point was not replayed.
According to her she had the ball on her racquet and her swing was affected by the fault call, resulting in her not going through with her return.
Wozniacki argued the point with the chair umpire: "Are you kidding? I had the racquet on the ball.
"He called it out, that's not my fault.
"Are you serious? That's not my fault.
"I had the ball on my friggin' racquet. It (the fault call) disturbed me."
But her pleas fell on deaf ears and after breaking only once from eight opportunities in the final set - and four times from 15 for the match - she would go on to surrender meekly in the end as she dropped serve and was beaten in 148 minutes.
Wozniacki has faced plenty of questions during her career about the fact that she reached the top of the rankings without having won a major, especially in light of results like Monday's, but she has for the most part handled such inquiries politely and with little frustration.
Perhaps the next time she is asked such questions she should adopt the attitude she did when riled by the fault call that was overturned against Kuznetsova, and she definitely should bring it out more often to fire herself up at crucial times during matches.
Otherwise when Wozniacki gets to the end of her career she might look back with regret on the opportunities that she blew considering the obvious physical ability that she has.