World number one Rafael Nadal had a tough start against USA's Mackenzie McDonald.
McDonald, ranked 65 in the world, stunned the Spaniard by winning the first set and opening the second set by immediately breaking Nadal's serve for a 2-0 lead.
Nadal was forced into a medical timeout in the second set, and both players left center court as McDonald held a 5–3 lead.
The crowd hovered in uncertainty, until the Spaniard returned on seemingly good legs.
The third set also offered drama, when the players were tied at 5–5.
Then McDonald managed to break and had the chance to serve for the win, which he managed after some drama.
The final scores were 6–4, 6–4, 7–5.
Italy's Jannik Sinner, seeded 15th in the tournament, is also through after defeating Argentina's Tomás Martín Etcheverry, ranked 79th, in three straight sets, 6–3, 6–2, 6–2.
In the third round, Sinner may face South African Lloyd Harris or Hungary's Marton Fucsovic.
Unseeded Harris defeated Sinners compatriot Lorenzo Musetti, seeded number 17, in the first round.