Melbourne - Former winner Stan Wawrinka needed three tiebreak sets to overcome Italy's Andreas Seppi and reach the quarter-finals of the Australian Open on Sunday.
The Swiss fourth seed edged out the 89th-ranked Seppi, 7-6 (7/2), 7-6 (7/4), 7-6 (7/4) in two hours 44 minutes on Margaret Court Arena.
Wawrinka's victory sets up him for a match with either former finalist and French 12th seed Jo-Wilfried Tsonga or Britain's unseeded Dan Evans in the last eight.
The Swiss leads Tsonga 4-3 and Evans 1-0 in their previous head-to-heads.
In a tight struggle, Wawrinka only got two service breaks from his nine break point opportunities and dropped his serve twice to Seppi.
It was Wawrinka's ninth win in 12 encounters with Seppi, who knocked out Australia's big hope Nick Kyrgios in the second round of the tournament.
Wawrinka hit 17 aces, 53 winners and made 41 unforced errors in overcoming Seppi to move into the second week of the Grand Slam.
Among Wawrinka's three Grand Slam titles is his win over Rafael Nadal in Melbourne three years ago, when he became the first player to defeat the top two seeds en route to a major title since Spaniard Sergei Bruguera won 1993 Roland Garros.
Wawrinka also won the 2015 French Open and last year's US Open, both times conquering Djokovic.