The top two seeds in the singles draw won their round-of-16 matches Thursday at the Tennis Championships of Honolulu at the UH Tennis Complex.

No. 1 Whitney Osuigwe advanced to the quarterfinals when Emina Bektas retired due to injury while trailing 3-2 in the first set. No. 2 Nicole Gibbs beat Alycia Parks, 6-2, 6-2.

The only other seeded player to advance to today’s quarterfinals was No. 5 Usue Maitane Arconada. No. 4 Arina Rodionova, No. 6 Risa Ozaki and No. 8 Deniz Khazaniuk were eliminated Thursday.

The top-seeded doubles team of Maitane Arconada and Caroline Dolehide advanced to the semifinals after defeating Bektas and Tara Moore by walkover. Allura and Maribella Zamarripa, 16-year-old twins who spent their early years on the Big Island and moved to Northern California in 2008, lost to Jamie Loeb and Hayley Carter 6-1, 7-5.