South Africa's Kevin Anderson suffered a first round exit at the Italian Open clay-court event in Rome on Monday.
Anderson went down 6-3, 7-6 (7/5) to French young gun Ugo Humbert.
The 22-year-old Humbert, ranked No 42 in the world, faltered when serving for the match at 5-4 in the second set, but regained his composure to seal the match in the tie-break.
Anderson, a former world No 5 but currently languishing at No 119 after injury woes, got into the main draw on a protected ranking.
The Rome Masters 1000 event is a warm-up ahead of the French Open starting at Roland Garros on 27 September.
It's not confirmed whether Anderson will use next week's European Open in Hamburg to gain more preparation before the French Open.
Meanwhile Anderson's compatriot, Lloyd Harris, lost 6-4, 6-2 to Japan's Yuichi Sugita in the qualifying round for the Italian Open.
Harris, the world No 95, will play in a Challenger event in Italy next week as preparation for his French Open campaign.
Harris made the second round of the recently completed US Open in New York, while Anderson suffered a first round exit.
Collated results from the first day of the ATP and WTA clay-court tournament in Rome on Monday (x denotes seed):
Filip Krajinovic (SRB) bt Felix Auger-Aliassime (CAN x16) 6-4, 7-5
Casper Ruud (NOR) bt Karen Khachanov (RUS x11) 6-3, 3-6, 6-1
Kei Nishikori (JPN) bt Albert Ramos-Vinolas(ESP) 6-4, 7-6 (7/3)
Stefano Travaglia (ITA) bt Taylor Fritz (USA) 6-4, 7-6 (7/4)
Borna Coric (CRO) bt Cristian Garin (CHI x14) 6-4, 6-4
Lorenzo Sonego (ITA) bt Nikoloz Basilashvili (GEO) 6-3, 6-1
Marin Cilic (CRO) bt Alexander Bublik (KAZ) 6-7 (4/7), 6-2, 6-4
Ugo Humbert (FRA) bt Kevin Anderson (RSA) 6-3, 7-6 (7/5)
Grigor Dimitrov (BUL x15) bt Gianluca Mager (ITA) 7-5, 6-1
Jannik Sinner (ITA) bt Benoit Paire (FRA) 6-2, 6-1
Hubert Hurkacz (POL) bt Dan Evans (GBR) 6-3, 3-6, 7-5
Jasmine Paolini (ITA) bt Anastasija Sevastova (LAT) 6-2, 6-3
Dayana Yastremska (UKR) bt Camila Giorgi (ITA) 7-5, 6-7 (5/7), 6-4
Amanda Anisimova (USA) bt Donna Vekic (CRO x16) 7-6 (7/4), 7-6 (8/6)
Elena Rybakina (KAZ x10) bt Ekaterina Alexandrova (RUS) 6-0, 6-4
Marie Bouzkova (CZE) bt Ajla Tomljanovic (AUS) 6-3, 6-4
Danka Kovinic (MNE) bt Julia Goerges (GER) 6-1, 6-0
Magda Linette (POL) bt Jelena Ostapenko (LAT) 6-4, 6-3
Elise Mertens (BEL x11) bt Hsieh Su-Wei (TPE) 6-3, 6-1
Aliona Bolsova (ESP) bt Alison Riske (USA x13) 5-7, 7-6 (7/4), 6-3
Anna Blinkova (RUS) bt Jil Teichmann (SUI) 6-3, 6-3
Barbora Strycova (CZE) bt Veronika Kudermetova (RUS) 6-3, 6-3
- Compiled by Herman Mostert