Kristina Mladenovic has admitted that she needed time to refine her skills in singles tennis after climbing the rankings as a doubles player.
The French youngster has reached the second week of a Grand Slam for the first time, but the 22-year-old has revealed that living up to her reputation as a junior and in doubles has not always been easy.
Mladenovic told the US Open official website: "What was difficult for me the past few years was knowing when to play that kind of game.
"I play hard and strong from the baseline, but I love to play drop shots to come in to the net. Sometimes I still do the mistake and go too much for the drop shot.
"You never know what the key to success is. Maybe it's just about timing. I maybe needed some time for my game to take shape."
Mladenovic will play Ekaterina Makarova on Sunday for a place in the quarter-final against Roberta Vinci.
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