Serena Williams carried both the ASB trophy and her daughter, Olympia, after winning her first tournament in three years.Credit...Chris Symes/Photosport, via Associated Press

Serena Williams won her first singles title since giving birth, defeating the unseeded American Jessica Pegula, 6-3, 6-4, to win the ASB Classic on Sunday in Auckland, New Zealand.

The 38-year-old, who gave birth to daughter Alexis Olympia on September 1, 2017, lifted the trophy at the ASB Classic in Auckland, New Zealand, after defeating fellow American Jessica Pegula 6-3, 6-4.

“Oh, it feels good!” said Williams, winner of 23 Grand Slam singles titles. “It’s been a long time. I think you could see the relief on my face. It’s pretty satisfying just to get a win in the final. That was really important for me, and I just want to build on it. It’s just a step towards the next goal.”

Since returning to the tour in early 2018, Williams reached five other finals, failing to win a set in any of them.

But the wait for more silverware has called for Williams to dig deep for self-belief.

“You have to be your biggest cheerleader, especially if you’re feeling you’re not doing everything right — or even if you are doing everything right but things aren’t working out for you,” she added.

Williams now will prepare for the Australian Open, a tournament she has won seven times, which begins on 20 January.

She also announced she will donate her $43,000 Auckland prize to Australian bushfire relief.