Serena Williams admitted her return to tennis was “super hard” as she lost what was her first match in almost a year, against Jelena Ostapenko, at the World Tennis Championship in Abu Dhabi.

It was Williams’ first outing since winning her 23rd grand slam singles title at the Australian Open last January – while pregnant – before taking time out to have the baby.

She failed to fully rediscover her rhythm and quickly dropped the first set 2-6 to the Latvian Ostapenko, the French Open champion.

The 36-year-old American roared back to win the second set 6-3 before losing the decisive tie-break 5-10 in the exhibition match.

Williams admitted her mind wandered to her child, Alexis Olympia Ohanian Jr, during the match.

“Motherhood is phenomenal. I was a little worried out there and I looked at my camp and I was like ’Is Olympia OK?’. But it’s really good,” she said in her on-court interview.

“I’m excited, it’s good to be back on the court. This was such a good time for me.

“It’s my first time playing in Abu Dhabi so thank you guys for the support. First matches back are always super incredibly hard, especially after having a baby but it was great, I’m glad I could do it here.“

Williams has registered for the Australian Open, which begins on 15 January at Melbourne Park.