Her greatest success was Scottsdale 2003. Beating Lindsay Davenport in the second round, she went on to defeat Eleni Daniilidou to progress to the semifinals. Scheduling problems forced both the semifinals and finals matches - for both singles and doubles - to be played on the Sunday of the tournament. Thus in a single day, Sugiyama managed to save a matchpoint in the semifinals against Alexandra Stevenson, rally from a set down to defeat doubles partner Kim Clijsters in the final, and then secure victories in both doubles matches to raise both trophies. The year 2003 proved to be her best year ever, pushing Serena Williams to the limit at Roland Garros and reaching the round of 16 in Wimbledon and US Open where her fourth round loss to Francesca Schiavone at Flushing Meadows was rather controversial. She finished the year ranked 10th, having defeated world No. 1, Justine Henin, in the round robin section of the season-ending championships. She also won a total of eight doubles titles that year, seven with Kim Clijsters (Sydney, Antwerp, Scottsdale, Roland Garros, Wimbledon, San Diego, Zurich) and one with Liezel Huber (Linz).