Carlos Alcaraz has called himself for breaking the rules at the French Open and conceded a point during his four-set victory over Ben Shelton.

Frances Tiafoe joined his fellow American in the last-eight with a straight-sets victory over Daniel Altmaier. The 15th seed had never previously made it beyond the third round at Roland Garros, but he will face Lorenzo Musetti or Holger Rune for a place in the semi-finals.