Danielle Collins has begun treatment for rheumatoid arthritis, a chronic inflammatory condition that causes pain and swelling in the body's joints.

The American, 25, who is the WTA World No.33 and reached the Australian Open semifinals in January, becomes the second leading WTA player to be diagnosed with RA in the past two seasons following Denmark's Caroline Wozniacki.

Read more: Caroline Wozniacki diagnosed with rheumatoid arthritis  

“I have not been feeling all that great for quite some time, but it has been somewhat of a relief and completely validating to understand the cause behind my pain,” Collins wrote on Instagram.

“As I have started treatment, I am looking forward to embracing this next challenge in life. Without a doubt, every healthy day is a gift and I am one hundred percent committed to keeping strong and continuing to battle on and off the tennis court.

“While I don’t know for sure what my journey to recovery will be, I do know that I feel really positive about getting back on the court.

“I feel like now I can get better and address my body’s needs in fighting this disease.”

Collins’ medical team believes she had been suffering from the condition for some time but it was not until recently she was diagnosed with rheumatoid arthritis.

“It's a huge relief to get a diagnosis because as an athlete, everything is physical for me and now I can plan to attack this disease with a strategic management plan,” said Collins.

Collins’ plan includes heavily involving her team to examine and identify the best approach to mitigate the effects of the condition.

This includes adjustments to her diet, and tailoring off-the-court training and conditioning as well as adjustments to her playing schedule to accommodate the recovery time that her body now needs.

“As an professional athlete, you are constantly reminded that your body is your temple," added Collins.

"Everything is physical for me, and I’ve come to appreciate how both mental and physical conditions are aligned - how every muscle and joint in the body is in tuned with one another. My health is the utmost of importance to me and I’m ready to take on the fight of rheumatoid arthritis."

Collins’ primary care physician Dr Clifton Page said modern treatments “can manage symptoms, limit joint destruction and preserve the longevity of athletes' careers.”

“For the elite athlete, rheumatoid arthritis is not a career-ending diagnosis,” he said in a statement.

"Being educated on the disease and having a good management plan can help keep athletes playing at their maximal potential. Treatment includes not only taking the proper medication to limit flare ups, but proper diet, rehab, rest and recovery.”

Read more: Rheumatoid Arthritis - The Facts