The Russian ninth seed overcame Sampras 6-2 6-4 6-7 7-6 in a three hours 33 minutes marathon under the closed roof of the Rod Laver Arena court.
The Russian is the only player in the last eight to have won a grand slam title — the 2000 U.S. Open — and meets South Africa’s Wayne Ferreira in the quarters.
In the women’s draw defending champion Jennifer Capriati bulldozed her way past Italy’s Rita Grande 6-3 7-6 to reach the last eight.
The top seed and world number one showed no sign of the hip injury which has been troubling her as she blasted her way through the opening set.
Grande’s finesse game came together in the second set but Capriati was simply too powerful.
She next meets seventh seed Amelie Mauresmo who was made to work hard for her 6-0 4-6 7-5 win over German Marlene Weingartner.
Belgium’s Justine Henin wasted no time, however, marching through with a no-nonsense 6-0 6-3 victory over 12th seed Elena Dementieva in an early match.
The sixth-seeded Henin barely put a foot wrong against Dementieva and meets compatriot Kim Clijsters in the quarters. Clijsters walloped Slovak Janette Husarova 6-0 6-2.
Former world number one and 1998 runner-up Marcelo Rios beat 23rd seed Nicolas Lapentti 7-5 6-1 6-4 to reach his first grand slam quarter-final since 1999.
There the Chilean will clash with Germany’s Tommy Haas after the seventh seed dug deep to beat Switzerland’s Roger Federer 7-6 4-6 3-6 6-4 8-6 in a titanic tussle.
The German’s three hours 35 minutes victory came after he had saved a match point in the fifth set.
But the real drama was reserved for the night match. With rain still falling on Melbourne Park, Safin and Sampras took to the court with the retractable roof closed.
Safin blitzed Sampras in the first two sets but the great champion punched back with some inspired net play to peg the Russian back to two-sets-to-one.
The pair were neck-and-neck in a thrilling fourth set tiebreak where Safin’s nerve held.
Broken early on in the tiebreak, Safin grabbed it back when Sampras missed a simple volley.
Buoyed, the Russian smacked two forehands for winners to move 5-4 ahead and two points from victory.
Sampras levelled with a heavy delivery and moved 6-5 ahead and set point with a deft drop volley.
Safin saved it, ripping a backhand down the line, and earned his first match point with a theatrical backhand into the corner.
He blew it by rolling a nervous forehand pass into the top of the net, however.
Sampras reached his second set point by burying a smash in the stands but again Safin fended it off with another geometry-defying backhand.
His 22nd ace fired at 208 kph brought up his second match point and an amazing forehand running pass, bent around the high part of the net, finally sank Sampras.
RESULTS:
MEN: Fourth round (prefix number denotes seeding): 9-Marat Safin (Russia) beat 8-Pete Sampras 6-2 6-4 6-7 (5-7) 7-6 (10-8); Wayne Ferreira (South Africa) beat Albert Costa (Spain) 4-6 6-4 6-4 6-7 (4-7) 9-7; 7-Tommy Haas (Germany) beat 11-Roger Federer (Switzerland) 7-6 (7-3) 4-6 3-6 6-4 8-6; Marcelo Rios (Chile) beat 23-Nicolas Lapentti (Ecuador) 7-5 6-1 6-4
WOMEN: 1-Jennifer Capriati (U.S.) beat 20-Rita Grande (Italy) 6-3 7-6 (11-9); 7-Amelie Mauresmo (France) beat Marlene Weingartner (Germany) 6-0 4-6 7-5; 6-Justine Henin (Belgium) beat 12-Elena Dementieva (Russia) 6-0 6-3.
Men’s quarter-final draw: Marcelo Rios (Chile) v 7-Tommy Haas (Germany); Wayne Ferreira (South Africa) v 9-Marat Safin (Russia); 26-Jiri Novak (Czech Republic) v Stefan Koubek (Austria); Jonas Bjorkman (Sweden) v 16-Thomas Johansson (Sweden)
Women’s quarter-final draw: 1-Jennifer Capriati (U.S.) v 7-Amelie Mauresmo (France); 4-Kim Clijsters (Belgium) v 6-Justine Henin (Belgium); Adriana Serra Zanetti (Italy) v 3-Martina Hingis (Switzerland); 8-Monica Seles (U.S.) v 2-Venus Williams (U.S.)—Reuters