Wawrinka, the champion in 2015 and the beaten finalist last year, won the first set but eventually lost 2-6, 6-3, 6-4, 6-7(5), 6-3.

The Swiss, who has struggled this year following knee surgery, will now tumble down the rankings and could fall outside the world's top-250.

Argentina's Marco Trungelliti was another star today after deputing for injured Australian Nick Kyrgios.

Trungelliti was only called-up as a lucky loser yesterday and drove 650 miles yesterday from Barcelona in a hire car with his brother, mother and 88-year-old Grandmother to make it in time.

Despite not picking up his racket for four days, the 28-year-old then dispatched another Australian in Bernard Tomic 6-4, 5-7, 6-4, 6-4 to reach the second round.

Novak Djokovic also progressed after a 6-3, 6-4, 6-4 win over Brazilian qualifier Rogerio Dutra Silva.

The Serb, seeded 20th, is seeking a first Grand Slam title since his victory in Paris in 2016.

Austria's seventh-seed Dominic Thiem was another winner in the men's draw when beating Ilya Ivashka of Belarus 6-2, 6-4, 6-1.

Eighth seed Petra Kvitova of Czech Republic was forced to battle from a set-down before defeating Veronica Cepede Royg of Paraguay 3-6, 6-1, 7-5

Second seed Caroline Wozniacki prevailed 7-6(2), 6-1 win over American Danielle Collins.

But Belarus' ex-world number one Victoria Azarenka lost 7-5, 7-5 to Czech Republic's Katerina Siniakova.

Men's top seed Rafael Nadal is currently leading Simone Bolelli of Italy in his first-round clash.

The Spaniard won the first two sets 6-4, 6-3 before the encounter was delayed overnight due to rain.