Hewitt dumped out by Giraldo
Lleyton Hewitt suffered a first-round exit at the Mutua Madrid Open as he lost to qualifier Santiago Giraldo.
In a two-and-a-half-hour marathon, Giraldo eventually prevailed 7-5 4-6 6-2, despite Hewitt saving 10 of 14 break points.
The four seeds in action on Monday all advanced, with number nine John Isner dispatching qualifier Teymuraz Gabashvili 7-6 (10/8) 6-4, and 10th seed Kei Nishikori beating Ivan Dodig 6-4 6-4.
Eleventh seed Jo-Wilfried Tsonga had a harder time seeing off Edouard Roger-Vasselin 6-3 4-6 6-3, while number 15 Mikhail Youzhny beat Benjamin Becker 6-3 6-4.
Twelfth seed Grigor Dimitrov was a 6-2 6-4 winner over Pablo Carreno Busta.
There were also wins for Jarkko Nieminen, Gilles Simon, Fernando Verdasco, Dominic Thiem and Feliciano Lopez.
Wildcard Marius Copil and lucky loser Marinko Matosevic joined those booking their place in the second round.
Before the start of the evening session a number of players, including the likes of Andy Murray, had gathered on court to pay tribute to former British number one Elena Baltacha, who died of liver cancer on Sunday.
In the women's tournament, ninth seed Dominika Cibulkova barely had time to settle in before she was sent packing by Samantha Stosur, losing 6-4 6-0.
All the other seeds advanced unscathed, with number two Li Na leading the charge into the second round with a 6-1 7-6 (9/7) win over Kirsten Flipkens.
Third seed Agnieska Radwanska saw off Eugenie Bouchard 7-6 (7/3) 6-2 while number four Simona Halep and number six Jelena Jankovic both enjoyed straightforward wins.
Number 15 Sabine Lisicki was given a workout before beating Karolina Pliskova 6-2 6-7 (5/7) 6-3 while there were also wins for Carla Suarez Navarro, Irina-Camelia Begu, Anastasia Pavlyuchenkova, Caroline Wozniacki and Svetlana Kuznetsova.