Top-seeded Daniil Medvedev withstoof a stiff test from Giovanni Mpetshi Perricard, but defending Dubai champion Ugo Humbert fell to Tallon Griekspoor.

The former junior No 1 took out Aleksandar Vukic in an epic atmosphere.

Find out more about the challenger gem that so many top players have been flocking to.

On a day in which Top 8 seeds Alex de Minaur, Andrey Rublev and Arthur Fils all fell, top-seeded Daniil Medvedev survived Jan-Lennard Struff 6-4, 7-6(4).

Shelton got his first win over Italy's Flavio Cobolli on Monday in Acapulco.

Sebastian Baez beat Alexandre Muller 6-2, 6-3 to claim his seventh career title and become the first man to in multiple Rio titles.