Australian duo Alex de Minaur and John Millman have both suffered early exits at the ATP Italian Open in Rome.
De Minaur, still searching for form after recovering from a pectoral injury sustained in March, was attempting to end a three-match losing streak and claim his first win on clay this season.
But despite taking the first set against Italian 16th seed Marco Cecchinato – who he beat in their only previous meeting at Wimbledon last year – Aussie No.1 De Minaur slipped to a 6-4, 3-6, 1-6 defeat as his opponent reached the second round for the second successive year.
However, the Italian has good pedigree on the surface, winning all three of his ATP Tour titles on the red dirt, including at the Argentina Open in February.
Millman, meanwhile, lost 3-6, 6-3, 6-4 in two hours, 10 minutes to British qualifier Cameron Norrie, who now faces Croatia's Borna Coric in the second round.
Norrie, who had to go through two matches to reach the main draw, has the extra incentive of facing Roger Federer in the third round if he can progress.
Australia's No.2 Nick Kyrgios, who made a first-round exit on his debut outing of the season on clay at the Madrid Open, will face 12th-seeded Russian Daniil Medvedev on Tuesday night (AEST).
Elsewhere, Canadian Denis Shapovalov set up a clash with world No.1 Novak Djokovic when he beat Pablo Carreno Busta in straight sets in his first round match.
The 20-year-old, who last year became the youngest player to reach the top 30 since 2005, put a four-match losing streak behind him as he beat the Spaniard 6-3, 7-6 (7-5).
France's 15th seed Gael Monfils lost 6-3, 6-1 to Spanish qualifier Albert Ramos-Vinolas in 61 minutes.
Fernando Verdasco produced a remarkable comeback to beat Britain's Kyle Edmund 4-6, 6-4, 6-2. After losing the first set and trailing 4-1 in the second, the Spaniard won 10 games out of the next 13 to claim the victory.
Italian Fabio Fognini continued his progress towards breaking into the world's top 10 with a 6-3, 6-4 win over Jo-Wilfried Tsonga.
The 10th seed outmanoeuvred the Frenchman in baseline rallies to win in one hour and 23 minutes.