Venus Williams was sent packing on the opening day of the Australian Open following a shock first-round loss to unseeded Swiss Belinda Bencic.

Last year's runner-up and fifth seed Williams followed fellow American and US Open champion Sloane Stephens out of Melbourne Park at the first hurdle - upstaged 6-3 7-5 by Bencic on Monday. This will be the first time since 1997, that Venus has not progressed to the second round of the Australian Open. 

Williams was flying the family name in Melbourne this year after sister and 23-time grand slam winner Serena withdrew from the tournament after giving birth in September.

Venus - a seven-time major winner and a runner-up at the Australian Open on two occasions - crashed out to 20-year-old Bencic on Rod Laver Arena as a slam was left without a Williams sister in the second round for the first time since the 2011 French Open.

The 37-year-old was broken five times and tallied 26 unforced errors in the defeat lasting one hour, 53 minutes against Hopman Cup champion Bencic. Bencic, who teamed up with Roger Federer to win the team event in Perth, will face either qualifier Luksika Kumkhum or Johanna Larsson in the next round.

Meanwhile, Irina-Camelia Begu stunned 31st seed Ekaterina Makarova 3-6 6-4 8-6 and world number nine Coco Vandeweghe was eliminated by Timea Babos.