Britain's new number one Elena Baltacha may need as long as two years to fully recover from liver damage.
The 19-year-old Scot has finally learned the source of the mystery viral infection that has affected her recently.
A specialist informed Baltacha the damage was caused by repeatedly taking antibiotics for tonsilitis and other infections.
She was told she is fortunate to emerge without lasting damage to her health, but can continue to play, providing she rests if over-tired.
The good news is that the damage is not permanent and that she will recover
Baltacha's coach Alan Jones
"To be confronted by that at the age of 19 was very frightening," said her coach Alan Jones. "The connotations were huge.
"No wonder she has been so fatigued. She was suffering a double-edged attack to her system and was being made to work hard all through it.
"The good news is that the damage is not permanent and that she will recover.
"She's given everything while being ill for 18 months, which makes you wonder what kind of career she will have when she's rid of all of this."
Despite her ailments Baltacha has risen to a career-high ranking of 154, and hopes to break through on the WTA's main circuit next year.
'Bored to hell'
She hoped to qualify for a Grand Slam for the first time at the Australian Open in January.
But that ambition will depend on whether her liver takes two or 24 months - the parameters suggested by the specialist - to recover.
Baltacha will also investigate whether she can treat her infections by means other than the two kinds of antibiotics she was using.
She has yet to decide whether to compete in a Challenger tournament in Southampton next week, but is raring to return to action.
"She has been bored to hell and scared and wants to get back on court," Jones added.
"It doesn't matter if she wins or loses. Right now only her self-esteem matters."