Complex sentence: At the US Open Keys was seeded for the first time at a Grand Slam, at number 27, but had a disappointing second round loss to Serbian qualifier Aleksandra Krunić, a match where both players had won the same amount of points.
Split into simpler sentences: At the US Open Keys was seeded for the first time at a Grand Slam, at number 27. But she didn't stay in New York long, as she had a disappointing second round loss to Serb qualifier Aleksandra Krunic where both players had won the same amount of points.