World No.2 Li Na secured her place in the third round of the Madrid Open on Tuesday with a comfortable 6-2 6-3 win over Chinese compatriot Zheng Jie.
Zheng had led the head-to-head record between the two 4-3 before the match, but Li has won the past four meetings between the pair in straight sets.
She will face 16th-seeded American Sloane Stephens or Petra Cetkovska in the last 16.
Lucie Safarova of the Czech Republic is also through to the third round, beating Slovakian Magdalena Rybarikova 6-1 6-2.
In men’s first-round action, Dutchman Igor Sijsling upset No.14 seed Tommy Haas of Germany 3-6 6-1 6-4.
Kevin Anderson of South Africa defeated Czech veteran Radek Stepanek 3-6 6-3 6-4, while Ernests Gulbis of Latvia accounted for Poland’s Jerzy Janowicz 7-6 (7-5) 3-6 6-2.