With those results, it was obvious that she would eventually claim the Number 1 ranking, which she did in Toronto that year. Having won two hardcourt tournaments, Clijsters was the strong favourite to win the U.S. Open, but she lost again in the ultimate stage to Henin-Hardenne. She ended the year 2003 with nine titles, the year-ending WTA Championships and 90 victories, more than anyone else on the Tour.

Injury worries started in 2004 when in her very first event of the year (the Hopman Cup), Clijsters twisted her ankle badly and had to withdraw from the tournament in Sydney. She was still able to reach the Australian Open final a few weeks later, her fourth Grand Slam final, but lost yet again to Henin-Hardenne.

After winning Tier-II titles in Paris and Antwerp, the biggest tournament in Belgium, Clijsters injured her wrist at Indian Wells and was out of the tour until September, which caused her to suffer a huge drop in the rankings. Clijsters came back in Hasselt, but injured her wrist again and was out for the reat of the year. Even though she was injured for most of the year, Clijsters still ended the year with a 20-2 record, her only losses coming to Henin-Hardenne in the Australian Open final and her retirement against Elena Bovina in Hasselt.

Clijsters still needed more rehabilitation and missed the first three months of 2005. She first came back in Antwerp, where she reached the quarters, losing to Venus Williams. Then she won two of the biggest tournaments of the year, Indian Wells and Miami, upsetting six top-10 players. Her WTA ranking jumped from 133 to 17 in the world, and she became the first unseeded player to win a Tier-1 tournament.

But during the clay season, where she admitted disliking the surface, she badly injured her knee against Patty Schnyder in Berlin and arrived at Roland Garros less than 100 per cent  fit, but still reached the fourth round, where she lost to Lindsay Davenport after leading 6-1, 3-1. But this is where her best-ever run started. During the summer, she won five of the seven tournaments she entered, including her very first Grand Slam title, upsetting three top 10 players on her way to victory. She ended the year not far from the No. 1 ranking, with nine titles and an outstanding 67-9 win-loss record.

The injuries hit Clijsters again right at the start of 2006 and she had to withdraw from Sydney with a hip injury, and even though she was able to reach the semifinals of the Australian Open (losing to eventual champion Amelie Mauresmo), she had to retire from that match with a twisted ankle in the middle of the third set. She was back a month later, reaching the final of Antwerp, but re-injured her foot and wasn't able to defend her Indian Wells title. She did have some good results during the spring and the summer, winning in Warsaw and Stanford and reaching the semifinals of the French Open and Wimbledon, but horrible news hit her in Montreal; she felt pain again in her wrist. She still tried to play, but fell on it and damaged it even more.  She did come back to win Hasselt in October and managed to reach the semifinals of the WTA Championships in Madrid where she lost to Mauresmo, but Clijsters has had enough of all these injuries:

Kim will start 2007 in Australia, where she has always had great results. She stated she wouldn't play much during the clay season, and is eager to play in her home tournament in Antwerp. We can also expect to see her in the spring hardcourt season and the grass season.

After Wimbledon, Kim and Brian will marry, but we still don't know what will happen afterwards although the fans will be hoping that she can end her career on a positive note, perhaps with another Grand Slam title under her belt. With the reputation of being the kindest and the most sociable player of the Tour, along with her unique ability to do splits on the court, the coming seasons will be far less interesting without her.