The reigning Wimbledon champion is by far the biggest scalp in the career of Suarez Navarro, who was a surprise quarter-finalist at last year's French Open.

The Spaniard was at a loss to explain the upset.

Poll

Who will win the Punjab Elections?

BJP 32.84%

AAP 41.79%

INC 25.37%

Submit

View All In Poll

"I donn't know, I only play, I don't know what to say," she said before a roaring crowd at the Rod Laver Arena.

Venus broke Suarez Navarro in the opening game, using a height advantage of almost 25 centimetres (10 inches) to attack the net.

She also overpowered the Spaniard with her serve, with Suarez Navarro showing early signs of nerves during her debut appearance on Melbourne's centre court, going down another break in the fifth game.

Venus served out the first set after 29 minutes looking poised for a rout.

But Suarez Navarro settled in the second set, snatching a break in the second game off a Venus double fault then holding to go up 3-0.

The American lifted her intensity, taking off her earrings in a sign she wanted no distractions, and broke back in the seventh.

Suarez Navarro refused to wilt, successfully drawing Venus into a baseline slugfest to regain the advantage in the next game with a backhand down the line that left the Wimbledon champion with no chance.

She was rewarded with three set points, Venus hitting a forehand long in the final one to give Suarez Navarro the set after 42 minutes.

The Spaniard went toe-to-toe with Venus early in the third, fending off a break point for the American in the second game.

Venus finally achieved a break in the fourth as Suarez Navarro double faulted in windy conditions, only to come within a point of surrendering the advantage in the next.

She held on with an ace to go 3-1 up but struggled to maintain control of the match and Suarez Navarro broke back in the ninth to make it 5-4.

Venus reached match point with the Spaniard serving in the next but hit her return long and her opponent evened the score at 5-5.

Suarez Navarro turned the tables to earn two match points at 6-5, netting the first but winning after Venus' return went long.