Paris - German fifth seed Alexander Zverev needed another five-setter to reach the Roland Garros last 16 on Saturday, defeating Serbia's Dusan Lajovic 6-4, 6-2, 4-6, 1-6, 6-2.
Zverev, whose best run at a Slam came in Paris last year when he made the quarter-finals, will face Italy's Fabio Fognini for a place in the last-eight.
Zverev, 22, had also needed five sets to defeat Australia's John Millman in the first round.
On Saturday, he hit 18 aces and 52 winners past 30th seed Lajovic, the runner-up to Fognini on Monte Carlo clay in April.
Results from the seventh day of the French Open on Saturday (x denotes seeding):
Fabio Fognini (ITA x9) bt Roberto Bautista Agut (ESP x18) 7-6 (7/5), 6-4, 4-6, 6-1
Alexander Zverev (GER x5) bt Dusan Lajovic (SRB x30) 6-4, 6-2, 4-6, 1-6, 6-2
Stefanos Tsitsipas (GRE x6) bt Filip Krajinovic (SRB) 7-5, 6-3, 6-7 (5/7), 7-6 (8/6)
Simona Halep (ROM x3) bt Lesia Tsurenko (UKR x27) 6-2, 6-1