Four-time Australian Open champion Roger Federer faces a giant challenge from revenge-bent Frenchman Jo-Wilfried Tsonga in the fourth round on Monday night.
Tsonga, the powerful and charismatic 2008 runner-up, beat the Swiss 17-time grand slam champion in straight sets in last year's French Open.
But he lost a five-set quarter-final to Federer at last year's Australian Open.
Immediately after downing countryman Gilles Simon in the third round on Saturday night, Tsonga declared his desire to atone for that defeat.
If he does, it will be the first time Federer has fallen short of the semi-finals at Melbourne Park since 2003.
It would also mean three consecutive majors in which the Swiss great has been beaten before the quarter-finals, after reaching at least the last eight for the previous 36 slams straight.
And it would cost Federer his place as Switzerland's top-ranked player, after 13 years in that position.
Stanislas Wawrinka, who is world No.8, two spots behind Federer, is poised to potentially overtake him after booking a quarter-final berth.
Earlier on Monday, world No.1 Rafael Nadal will face Japanese 16th see Kei Nishikori.
Fourth-seeded Scot Andy Murray meets French lucky loser Stephane Robert and Bulgarian Grigor Dimitrov faces Spain's unseeded Roberto Bautista Agut in Monday's other men's matches.
In the women's draw, defending champion Victoria Azarenka will meet Sloane Stephens for the first time since beating the American in controversial circumstances in last year's semi-finals.
The Belarusian called a medical time-out after coughing up five match points while trying to serve out her clash with Stephens, but later defended herself against accusations of gamesmanship, insisting she was genuinely injured.
Third seed Maria Sharapova plays Dominika Cibulkova, fifth seed Agnieszka Radwanska takes on unseeded Spaniard Garbine Muguruza and Jelena Jankovic faces Simona Halep.