At the Indian Wells Open in early 2001, Clijsters finally defeated Hingis in her fourth meeting against the world No. 1 player to reach her first Tier I final. After winning the first set of the final, she ended up losing in three sets to Serena Williams. The match was overshadowed by the controversy of the crowd booing Williams for her sister Venus's late withdrawal from their semifinal, leading to both sisters boycotting the tournament for 14 years. A few months later at the French Open, Clijsters became the first Belgian to contest a Grand Slam singles final. She had defeated No. 16 Henin in the semifinals in their closest and highest profile match to date, coming back from a set and a break down, and also having saved three break points that would have put her behind 5–2 in the second set. The final against Australian Open champion and world No. 4 Jennifer Capriati was an even tighter match. Playing a day after her 18th birthday, Clijsters won the first set but lost the second. After a French Open final record 22 games and 2 hours 21 minutes in total, she was defeated by Capriati 12–10 in the deciding set. The match was ranked as the greatest French Open women's final in Open Era history by "Tennis.com". Clijsters would go on to make it to at least the quarterfinals at each of the next three majors. She also played in her first Grand Slam doubles final at Wimbledon later that year, with Ai Sugiyama as her partner. She won three singles titles in 2001, including her second titles at both the Luxembourg Open and the Sparkassen Cup, to help her finish the season at No. 5 in the world. With four doubles finals in total, she was also ranked No. 15 in doubles at the end of the year.