Serena Williams delivered a stellar display at the Auckland Open, saying she was "in the zone" in a thrashing of Amanda Anisimova on Saturday.

Williams needed just 44 minutes to crush 18-year-old Anisimova 6-1 6-1 in the semi-finals of the WTA International event.

The 23-time grand slam champion was in fine form in the lead up to the Australian Open, producing 17 winners and six unforced errors to move into the final against Jessica Pegula.

"I was definitely in the zone today. It was just one of those days," Williams said during an on-court interview.

"I knew I was playing a really, really great player and an even better person so I knew I had to come out serious."

Williams added: "It feels good. I've been working really hard for a couple of years.

"My daughter is only two, I tend to be really hard on myself, but considering everything I'm doing pretty good."

Williams moved into a 98th WTA Tour final and will be aiming for a 73rd title and first since the 2017 Australian Open.