Top-ranked Naomi Osaka comfortably beat Dominika Cibulkova 6-3, 6-3 in the first of her two matches at the Italian Open on Thursday.
With play backed up following a rainout on Wednesday, Osaka was also to play Mihaela Buzarnescu or Julia Goerges for a spot in the quarterfinals.
Osaka can hold on to the No. 1 ranking by reaching the quarters.
Osaka also beat Cibulkova in straight sets last week in Madrid.
Roger Federer, Rafael Nadal, and Novak Djokovic also need to win twice on Thursday to reach the last eight.
Distracting players on Thursday were fighter jets above the Foro Italico rehearsing for an air display later. Players often appeared bothered by the noise and flybys.