Sugiyama began 2005 with four consecutive first-round losses. She lost in the first rounds of the first three Grand Slams; only at San Diego did she really do well, making it to the final, which she lost 0–6, 3–6 to Mary Pierce, having defeated Daniela Hantuchová, Sesil Karantacheva and Svetlana Kuznetsova en route. Sugiyama also reached the final in doubles with Hantuchová, losing to Virginia Ruano-Pascual and Conchita Martínez. She broke her Grand Slam "curse", reaching the third round before losing to Clijsters, the eventual champion.