Serena Williams says she’s ready to rejoin the women’s tennis tour after a bout with pain and injuries that caused the world No.1 to cut short her 2015 season.

Williams last played in a competitive match in a shock semi-final loss to Italian Roberta Vinci at the US Open in September, missing out on a calendar-year sweep of the Grand Slams.

“I never lacked motivation. I just was really injured,” she told reporters in Manila on Sunday without discussing the nature of the injury.

“I’ve always been motivated, so I just had to get better — you know, be able to just walk without being in pain.”

Williams has said she played injured most of the year as she racked up her Grand Slam win count to 21 by taking Wimbledon as well as the Australian and the French Open crowns.

After her loss to Vinci she pulled out of the China Open and the year-ending WTA Finals, saying she needed “time to heal”.

She cited injuries to “my elbow, my knee, or, in the final moments after a certain match in Flushing, my heart”.

Her coach Patrick Mouratoglou has also told ESPN she was lacking “motivation” after the US Open loss.

“It was good to be back here,” Williams said Sunday as she played two sets in the IPTL’s abbreviated format representing the Philippine Mavericks team against Ivanovic’s UAE Royals.

The teams play five sets of men’s and women’s singles, men’s and mixed doubles as well as one for “legends” or retired men’s players.

“It’s a good opportunity for me to get some more tennis in and get ready. I felt really good.”

Williams begins her 2016 season at the Hopman Cup in Perth on January 3 before defending her Australian Open title later that month.

She is one Grand Slam win shy of equalling Steffi Graf’s record 22 titles. The German also swept all four Grand Slam titles in 1988.