Eighth seed Alcaraz, regarded one of the best teenagers in men's tennis over the past decade, lost to American Sebastian Korda 7-6, 6-7, 6-3.

Albert Ramos-Viñolas of Spain knocked out Cameron Norrie of Britain, the seventh seed, 6-4, 2-6, 6-4.

Canadian sixth seed Felix Auger-Aliassime went out to the up-and-coming Italian Lorenzo Musetti in straight sets 6-2, 7-6 and unseeded Serbian Laslo Đere knocked out 16th seed Lorenzo Sonego of Italy 6-4, 6-4.

Fifth seed Andrey Rublev was the closest to an upset elsewhere, coming from a set down to defeat Australian Alex de Minaur 2-6, 6-1, 6-4 while second seed Zverev was able to overcome Federico Delbonis from Argentina to progress by a score of 6-1, 7-5.

Fourth seed Norwegian Casper Ruud won 7-6, 7-5 against Holger Rune of Denmark to go into the last 16, while young Italian ninth seed Jannik Sinner won in straight sets 7-5, 6-3 against Emil Ruusuvuori of Finland.

One of the odd incidents of the day was the retirement of Kazakhstan's Alexander Bublik who seemingly quit his match against Spanish 13th seed Pablo Carreño Busta who he was trailing 4-6, 7-6, 4-3.

Bublik has already said this week that he hates the clay season, despite entering the clay-court tournament.

Argentina's 12th seed Diego Schwartzman is through too with a 6-0, 7-6 victory over Hungary's Marton Fucsovics and 10th seed Taylor Fritz of the United States won in three sets 6-3, 4-6, 6-4 against Croatian veteran and 2014 US Open champion Marin Čilić.

Poland's 11th seed Hubert Hurkacz won in three sets too, knocking out Spaniard Pedro Martínez 6-3, 4-6, 6-4.

In the only unseeded match of the day, Belgium's David Goffin defeated Britain's Dan Evans in straight sets 7-6, 6-2.