Complex sentence: She continued her great streak at the tournament by defeating Marina Erakovic in round two, and in the third round upset the highest ranked teenager in the world, Elina Svitolina, in three sets, to reach her first ever WTA Tour quarterfinal.
Split into simpler sentences: She continued her great streak at the tournament by defeating Marina Erakovic in round two. In the third round she upset the highest ranked teenager, Elina Svitolina, in three sets, to reach her first ever WTA Tour quarterfinal.