Her quarterfinal win comes just one day after she registered the biggest win of her career against world No. 1 Simona Halep on Wednesday, reports Efe news.
The Australian world No. 15 got off to a slow start with some unforced errors that gave Mertens an advantage although she was back in the game by the middle of the first set.
Barty created two break chances in the second set and dominated the set, finally finishing off the game in straight sets after an hour and 17 minutes on court.
"It was nice and solid today. I was pretty happy with the way I was able to come out here and play," Barty said on court.
"For us, it's mostly been about how I try and play my game and not get too sucked into playing the way they (opponents) want me to play. It's important for me to serve well and look for forehands and try and be dominant from that first shot," Barty said after the match.
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