Jack Draper was controversially ruled to have caused a hindrance to opponent Daniil Medvedev as his Indian Wells title defence ended in the quarter-finals.
The 24-year-old Briton, looking understandably weary from his exploits in beating Novak Djokovic less than 24 hours earlier, went down 6-1 7-5 to the former world No1.
The decisive moment came at 5-5 and 0-15 in the second set when umpire Aurelie Torte decided to award Medvedev a point following a video review after Draper had raised his arms at a disputed line call and was deemed to have distracted his opponent, with Medvedev going on to seal a crucial break.
The California crowd made their feelings clear as Medvedev was booed at the change of ends and after sealing victory a short time later, although Draper shook hands with both Medvedev and Torte before leaving the court.
In a one-sided first set, Draper was broken in his opening service game after a net cord fell in Medvedev's favour at break point.
After rattling through his own service game, Medvedev produced winners down the line and cross court to move into a 4-0 lead after just 15 minutes.
Draper finally got on the board with a hold of serve to make it 5-1 but it was only a temporary reprieve as Medvedev wrapped up the set in 25 minutes.
The second set was a closer contest, although it was the Draper serve which was consistently coming under the greater pressure, with Medvedev telling his opponent he "didn't feel great" about the incident which ultimately contributed to him sealing a semi-final spot at the end of the match.
British interest in the singles came to an end as Cameron Norrie went down 6-3 6-4 to Carlos Alcaraz.
The British No2 fought gamely against the world No1 but was eventually outclassed.
Norrie struggled to land a blow on the Alcaraz serve in the early stages while struggling to hold his own and the 30-year-old was eventually broken in the sixth game of the contest.
Surprisingly that led to a temporary lapse of concentration from the Spaniard, who was broken back to love only to then force a third straight break before wrapping up the opening set.
Norrie gained an early break in the second set but his own service problems saw Alcaraz haul his way back in front.
Norrie saved the first three match points he faced but Alcaraz duly converted the fourth to set up a semi-final showdown with Medvedev.
In the women's singles, Elena Rybakina overcame Jessica Pegula in straight sets and will face Elina Svitolina in the last four.
