The American is coming off of a magical 2017 that saw her reach the finals here and at Wimbledon as well as the U.S. Open and the WTA Finals in Singapore as she regained a spot in the top five.
Bencic has recently regained some good form, riding a 15-match winning streak with three ITF Tour titles to end off last year which put her back into the Top 100 at #74 and two exhibitions, the Hopman Cup, teaming with Roger Federer and yesterday in Kooyong.
Williams' results leading up to Melbourne
The seven-time Grand Slam champion decided to take the opening week of the season off, opting to play in Sydney during the week prior to Melbourne.
As the second seed, she received a first-round bye before drawing Angelique Kerber in the second round. After rallying from 5-3 down to win the last four games to take the first set 7-5, Williams collapsed in the final two sets, losing 6-3 in the second and 6-1 in the third.
Bencic's results leading up to Melbourne
The former U.S. Open quarterfinalist won all of her Hopman Cup matches, recording singles wins over Naomi Osaka 7-5, 6-3, Anastasia Pavlyuchenkova 6-1, 3-6, 6-3 and Coco Vandeweghe 7-6 (6), 6-4.
In the mixed doubles with Federer, the duo beat Osaka and Yuichi Sugita 2-4, 4-1, 4-3 (5-1), Pavlyuchenkova and Karen Khachanov 4-3 (5-1), 3-4 (3-5), 4-1 and Vandeweghe and Jack Sock 4-3 (5-3), 4-2.
In the final, her winning streak was stopped by Kerber, losing 6-1, 6-4, but in the deciding match, Bencic and Federer triumphed over Kerber and Alexander Zverev 4-3 (5-3), 4-2.
In Kooyong, the Swiss played one match, the final (as is per tournament procedure), defeating German Andrea Petkovic 3-6, 6-4, 10-4.
Williams and Bencic have met on four occasions with the American taking all four. She won in the first round of Luxembourg 6-3, 6-1 in 2012, a 6-4, 6-1 thrashing in the first round of the 2014 French Open and two victories in 2015: 6-1, 6-2 in the second round of Dubai and 6-3, 6-4 in the third round of the U.S. Open.
Who will win?
The logic would be that Williams prevails, but Bencic is in very good form at the moment even if most of her recent wins are ITF and exhibition events. The fact that the fifth seed played one match and lost is not a concern as at 37, she needs to pace herself and losing to Kerber, who would go on to win in Sydney, is nothing to be ashamed of.
Bencic will look to blunt the Williams power by taking the ball early and redirecting shots down the line with her flat forehand and excellent backhand. To prevent the Swiss from doing this, the American must serve well to gain a lot of free points while utilizing her backhand, her more consistent wing. She'll also look to attack the Bencic serve, especially second balls.
This is a tough section of the draw for whoever gets out of this match as a third-round encounter with two-time Aussie Open semifinalist Ekaterina Makarova awaits and a possible Round of 16 clash with the red-hot Julia Goerges could also loom. Williams has finals points to defend, so a loss here could see her ranking fall a few spots depending on other results.
This will be the second match of the day on Rod Laver Arena, following the opening match between seventh seed Jelena Ostapenko and Francesca Schiavone. The winner of this match faces an unknown qualifier or Sweden's Johanna Larsson in the second round.
Prediction: Williams in three sets.