And she was joined by world number one Victoria Azarenka who crushed Elena Vesnina 6-3 6-3.
Russian world number two Sharapova blitzed the 90th-ranked Slovenian 6-0 6-2 in an hour and 14 minutes.
Despite the one-sided scoreline Hercog did put up some resistance, saving eight of the 14 break points and even breaking back at one point during the second set.
But there was no stopping the willowy Russian, who will face fifth seed Angelique Kerber in the last eight, the German having battled past 10th seeded Dane Caroline Wozniacki 6-1 2-6 6-4.
Belarus star Azarenka ended the hopes of Russian qualifier Vesnina in 92 minutes.
A single break of serve was enough to take the opening set and the US Open finalist broke a further three times in the second stanza to set up a meeting with Romina Oprandi.
Seventh seed Li Na is also in the quarter-finals after a hard-fought match against compatriot Peng Shuai, coming out on top of a tie-break in the third set to win 4-6 6-2 7-6(2). Li will face Poland's Agnieszka Radwanska in the next round.