Petra Kvitova diagnosed with mononucleosis on HWN SPORTS

It's been a disappointing season for two-time Wimbledon champion Petra Kvitova - but the tennis star now has a reason for the lethargy that has plagued her.

The world No. 4 has struggled to recapture the scintillating form she showed in trouncing Canadian starlet Eugenie Bouchard in the 2014 final at the All England Club.

Although triumphant at WTA Tour events in Sydney and Madrid in January and May respectively, Kvitova failed to make the second week at the Australian Open, Roland Garros or Wimbledon and was forced to pull out of events in Indian Wells and Miami due to fatigue.

Her preparations for the grass-court season were also curtailed by a sore throat, and her Wimbledon title defense ended in round three against Jelena Jankovic as Kvitova faded after winning the opening set.

Now the Czech star has revealed she has been diagnosed with mononucleosis -- a viral condition which can lead to prolonged fatigue, swollen glands, fever and body aches -- which could help explain her struggles with form and fitness.

Source: CNN, HWN Africa.