Janković ended her losing streak by beating world no.
17 Elena Likhovtseva in the first round of the Internazionali BNL d'Italia in Rome, before eventually losing to Venus Williams in three sets in the quarterfinals.
At the French Open, Janković reached the third round for the first time, where she lost to world no. At Wimbledon, Janković defeated sixth-seeded and defending champion Venus Williams in the third round in three sets.
Competing in the fourth round of a Grand Slam event for the first time, she lost to ninth-seeded Anastasia Myskina. 2 Justine Henin in three sets, after Janković had led 6–4, 4–2.
In 2007, she became the first Serbian player to win a Grand Slam title when she won the Wimbledon mixed doubles title with British partner Jamie Murray.
In October 2003, Janković entered the top 100 at no.
She went on to defeat Dinara Safina in the final to win the first Tier I title of her career. 1 Henin in three sets both in the semifinals of the J&S Cup in Warsaw and the quarterfinals of the Qatar Telecom German Open (failing to hold a 4–0 lead in the third set in the latter), Janković won her second career Tier I title at the Internazionali BNL d'Italia in Rome, defeating second-seeded Svetlana Kuznetsova in the final.
This results meant she entered the top 5 in the world rankings for the first time.
At Wimbledon, Janković was the third seed, but lost in the fourth round to the surprise eventual finalist Marion Bartoli.Because of her results at these tournaments, her ranking rose to world no.10, the first time she had been included in the top 10.This improved her ranking to a new career-high of world no 3.On grass, Janković captured the DFS Classic title in Birmingham, beating top-seeded Maria Sharapova in the final.Janković was the fourth seed at the French Open and one of the favorites for the title.