AUCKLAND, New Zealand - A highly-anticipated first round clash between two former World No.1s went the way of Venus Williams at the ASB Classic on Tuesday, as the seven-time Grand Slam champion won the last four games to defeat Victoria Azarenka, 6-3, 1-6, 6-3.

In a match that lived up to its billing and the pedigree of both players, Williams and Azarenka toiled for over two hours on Centre Court at the ASB Tennis Centre, and the American needed to dig deep to score her first win over the two-time Australian Open champion in five years. 

"Tonight was not easy, maybe one of the toughest first rounds I've ever played," Williams said on-court after the match. "She has the experience, and for the first match of the goal was to get past this first round, and we need these matches going into the Australian [Open].

"I'm hoping that the next round will be fruitful for me, and I already got a goal for 2019." 

Though it was Williams who got off on the right foot in the match, the Belarusian slowly worked her way into a leading position after losing five of the first six games of the match.

The American dug out of a 0-40 hole in a key third game of the opener, breaking Azarenka twice to build a 5-1 lead. From there, she held off the Belarusian's fight back to claim a one-set lead, but the 28-year-old was not ready to go quietly.

"I would say that my first serve percentage dropped a lot, and she made less errors," the American assessed. "Both of us, our ranking isn't as high, but it doesn't mean that we can't play, regardless of whatever the ranking is."

Azarenka later blitzed her way through the second set, where she served six of her nine aces in the match and saved all seven break points she faced, and twice built a break lead in the decider.

However, a key sixth game helped get the American back on course, as she broke serve from 40-0 down, and the World No.39 and 2015 champion did not lose another to book a spot in the second round opposite another former winner in Auckland, 2017 champion and American compatriot Lauren Davis.  

"Honestly, in the first match, you just want to get a rhythm. This is the second year in a row [that I] played a former No.1 in the world in the first match," Williams added. "At the end of the day, you just get your mind ready, and you get out there and say that I'm here to play tennis and I'm just here to perform.

"[Lauren] is very talented and she had an amazing summer here. It's going to be a match well-contested. I have a lot of respect for her and for her game. I'll be going out there and preparing, and hopefully get another win."