While second seed Li advanced past Australian qualifier Casey Dellacqua, Czech fifth seed Petra Kvitova was edged out of a hard-fought clash by China's Zhang Shuai 7-6 (8-6) 5-7 6-3.
Li dismissed left-hander Dellacqua 6-1 6-4 in one hour and 17 minutes, to move into the third round where she will meet either another Australian Sam Stosur or Russia's Elena Vesnina.
Kvitova had fought impressively to square the match having lost the opening set in a tie-breaker, but the world number six made a dreadful start to the final set - dropping serve twice to go 3-0 down.
The former Wimbledon champion showed plenty of fight to square the decider at 3-3, but then lost the final three games as Zhang sealed the upset win.
Seventh seed Angelique Kerber threw away her one-set advantage as she went down 4-6 6-3 6-4 to Czech qualifier Petra Cetkovska.
Cetkovska will now meet either 10th seed Sara Errani or Ekaterina Makarova after both won through their respective first-round clashes.
Errani came from 3-0 down in the first set to storm past South Africa's Channelle Scheepers 7-5 6-3, but there was bad news in store for her fellow Italians.
Roberta Vinci was felled by Russia's Makarova 6-2 7-6 (8-6) while wildcard Nastassja Burnett was thrashed by Spain's Garbine Muguruza 6-1 6-3.
Next up for Muguruza is another Italian, Francesca Schiavone.
American qualifier Christina McHale caused a stir by beating Romania's Sorana Cirstea 6-3 4-6 6-1, to book a second-round meeting with Italian wildcard Camila Giorgi.
Giorgi, ranked 54th, had given the capital crowd something to cheer early on when she knocked out ninth seed Dominika Cibulkova 6-4 7-6 (7-2).
Spain's 13th seed Carla Suarez Navarro edged German qualifier Mona Barthel 6-2 6-2, while Swiss qualifier Belinda Bencic was too good for Russia's Anastasia Pavlyuchenkova 6-3 3-6 6-3.
Puerto Rican qualifier Monica Puig overcame a second-set slip up to beat Slovakia's Daniela Hantuchova 6-0 4-6 6-0.