He entered the 2007 Australian Open as the ninth seed, and advanced to a fourth round.

In Marseille, Ančić retired in the first round and was diagnosed with mononucleosis.
Later, he confessed that he was playing sick a week before in a match against Germany in the Davis Cup, and the virus had started to affect him at the Australian Open.
Due to his illness, Ančić spent most of the next 10 weeks in bed and missed six months from the tour.

Ančić started training in June with his Swedish coach Fredrik Rosengren.
After he withdrew from two tournaments in July, Ančić returned in August at the Canada Masters and the Cincinnati Masters, where he lost in the second rounds.
Ančić fractured a small bone at the gym a week before the US Open, which was the third Grand Slam he missed in 2007.
In October, he made his first big result after the illness, making it into the quarterfinals at Madrid Masters.
In 2007, he dropped to No.
83 at the end of the year.

Ančić started the 2008 season again with illness and was forced to withdraw from the tournaments in Australia, missing his fourth Grand Slam in a row.
His first 2008 event was in Marseille in February, where he eventually lost in the final to Andy Murray.
At the Indian Wells Masters and Miami Masters, Ančić entered the main draw by receiving wild cards, where he beat three seeded players.

Having lost in an opening round at the Canada Masters, and having skipped the Cincinnati Masters as the fatigue intensified and the weight loss mounted, Ančić withdrew from the 2008 Summer Olympics, and later the US Open, due to a recurrence of mononucleosis.
Ančić returned in September, playing for the Davis Cup.
After a good start at the beginning of the 2009 season, Ančić announced in May that he would pull out of the French Open, Wimbledon, and the Davis Cup semifinal match, again because recurrence of mononucleosis.

Ančić returned to the main tour level at the 2010 BNP Paribas Open, where he made it to the third round.
He played Challengers without success.
He entered the 2007 Australian Open as the ninth seed, and advanced to a fourth round.
In Marseille, Ančić retired in the first round and was diagnosed with mononucleosis. Later, he confessed that he was playing sick a week before in a match against Germany in the Davis Cup, and the virus had started to affect him at the Australian Open. Due to his illness, Ančić spent most of the next 10 weeks in bed and missed six months from the tour.
Ančić started training in June with his Swedish coach Fredrik Rosengren. After he withdrew from two tournaments in July, Ančić returned in August at the Canada Masters and the Cincinnati Masters, where he lost in the second rounds. Ančić fractured a small bone at the gym a week before the US Open, which was the third Grand Slam he missed in 2007. In October, he made his first big result after the illness, making it into the quarterfinals at Madrid Masters. In 2007, he dropped to No. 83 at the end of the year.
Ančić started the 2008 season again with illness and was forced to withdraw from the tournaments in Australia, missing his fourth Grand Slam in a row. His first 2008 event was in Marseille in February, where he eventually lost in the final to Andy Murray. At the Indian Wells Masters and Miami Masters, Ančić entered the main draw by receiving wild cards, where he beat three seeded players.
Having lost in an opening round at the Canada Masters, and having skipped the Cincinnati Masters as the fatigue intensified and the weight loss mounted, Ančić withdrew from the 2008 Summer Olympics, and later the US Open, due to a recurrence of mononucleosis. Ančić returned in September, playing for the Davis Cup. After a good start at the beginning of the 2009 season, Ančić announced in May that he would pull out of the French Open, Wimbledon, and the Davis Cup semifinal match, again because recurrence of mononucleosis.
Ančić returned to the main tour level at the 2010 BNP Paribas Open, where he made it to the third round. He played Challengers without success.
Mario Ančić