Serena Williams will return to the WTA Tour for the first time in over 12 months when she takes the court against Zarina Diyas in the first round of the BNP Paribas Open on Thursday.

Williams has not played on the tour since announcing her pregnancy in April 2017. Williams’ only appearances after giving birth to daughter, Alexis Olympia, in September, were at the World Tennis Championships in Abu Dhabi in December, and playing doubles for the United States in the Fed Cup against the Netherlands in February earlier this year.

The 23-time women’s singles Grand Slam champion’s return to training was delayed after she revealed she suffered pulmonary embolism, which left her bedridden for the first six weeks after child birth.

"I almost died after giving birth to my daughter, Olympia,” Williams wrote in her column on CNN. “Yet I consider myself fortunate.”

“While I had a pretty easy pregnancy, my daughter was born by emergency C-section after her heart rate dropped dramatically during contractions. The surgery went smoothly. But what followed just 24 hours after giving birth were six days of uncertainty,” she added.

Serena Williams Serena Williams will make her competitive return WTA return Thursday at the BNP Paribas Open. Photo: Getty Images

Williams has now revealed that she is ready to return to action, but admitted she will not be at her best. The former world number one is confident she will get better as the season progresses and revealed she is ready to be patient as her journey back to full fitness will be slow.

“Yeah, it’s been hard. It’s been so many days but even now I ask myself how I can keep going on,” Williams told BBC Sport. “It’s been really really difficult, but I keep going. I know that I might not be at my best yet, but I am getting there.”

“Every day is a new day and every day I should be getting better. As long as I am moving forward even if it is at a turtle’s pace.

“I do feel I am ready otherwise I wouldn’t be here. I wouldn’t be playing. If I am not ready now I think I will never be ready,” the tennis great added. “I still feel like I am going to get better every day and in two months I will be way better than I am now and you have to start somewhere.”

The 36-year-old recently played singles for the first time this year as she joined the Tie Break Tens event in New York. Williams beat former Wimbledon champion Marion Bartoli in the first match before falling to China’s Zhang Shuai 11-13 in the semi-finals. Elina Svitolina won the event beating the Chinese star 10-3 in the finals.