The Spaniard was a comfortable winner over Canada’s Vasek Pospisil, beating the world No 60 6-2 6-4 6-4 to reach the last 16 and equal his best performance in a grand slam.
Wawrinka has yet to drop a set in Melbourne and enjoyed another straightforward victory in the third round, beating Finland’s Jarkko Nieminen 6-4 6-2 6-4 on Rod Laver Arena.
The fourth seed sent down nine aces and won 90 per cent of points behind his first serve to set up a clash with Spain’s Guillermo Garcia-Lopez in the fourth round.
Feliciano Lopez continued his charmed progress through the draw with victory over Poland’s Jerzy Janowicz, the 12th seed winning 7-6 (8-6) 6-4 7-6 (7-3) to set up a last-16 contest with eighth seed Milos Raonic.
Lopez saved three match points in his first-round match with wild card Denis Kudla, eventually winning the fifth set 10-8, and saved another in the second round against Adrian Mannarino.
Lopez was trailing 4-6 4-6 0-4 when Mannarino fell ill but won the third-set tie-break and was leading 4-0 in the fourth set when his unfortunate opponent retired.
Raonic continued the theme of one-sided matches by beating Germany’s Benjamin Becker – who knocked out home favourite Lleyton Hewitt in the previous round – 6-4 6-3 6-3.