Madrid - Record five-time Madrid Open winner Rafael Nadal pulled out of a media conference on Monday on the eve of his opening match at the tournament due to a stomach bug.
He is scheduled to fulfil his delayed media obligation on Tuesday, according to tournament officials, allaying concerns over his fitness.
Eleven-time Roland Garros champion Nadal had also been suffering from the bug on Sunday, a week on from losing in the semi-final of the Barcelona Open.
The 17-time Grand Slam winner is racing to make up for lost time after failing to win a clay title so far this spring.
The second seed is due to open play in the second round against Canadian teenager Felix Auger-Aliassime.
Results from the ATP and WTA tournaments in Madrid on Monday (x denotes seeding):
Laslo Djere (SRB) bt Dusan Lajovic (SRB) 6-4, 6-4
Reilly Opelka (USA) bt Pablo Carreno Busta (ESP) 7-6 (7/5), 6-4
Karen Khachanov (RUS x11) bt Jaume Munar (ESP) 6-4, 6-7 (5/7), 6-3
Frances Tiafoe (USA) bt Nikoloz Basilashvili (GEO x14) 6-7 (8/10), 6-3, 6-4
Philipp Kohlschreiber (GER) bt Mikhail Kukushkin (KAZ) 6-2, 7-6 (7/5)
Taylor Fritz (USA) bt Grigor Dimitrov (BUL) 7-6 (10/8), 7-6 (7/4)
Marin Cilic (CRO x9) bt Martin Klizan (SVK) 6-4, 2-6, 7-6 (7/0)
Gael Monfils (FRA x15) bt Andreas Seppi (ITA) 6-3, 6-1
Richard Gasquet (FRA) bt Alejandro Davidovich (ESP) 7-5, 7-6 (7/5)
Yulia Putintseva (KAZ) bt Pauline Parmentier (FRA) 6-4, 4-6, 6-3
Sloane Stephens (USA x8) bt Victoria Azarenka (BLR) 6-4, 2-6, 6-2
Kiki Bertens (NED x7) bt Jelena Ostapenko (LAT) 6-4, 6-3
Anastasija Sevastova (LAT x12) bt Mihaela Buzarnescu (ROU) 6-3, 6-4
Petra Kvitova (CZE) bt Kristina Mladenovic (FRA) 6-3, 7-6 (7/5)
Ashleigh Barty (AUS x9) bt Danielle Collins (USA) 6-1, 1-6, 6-1
Viktória Kužmová (SVK) bt Carla Suárez (ESP) 6-4, 7-6 (7/2)
Belinda Bencic (SUI) bt Svetlana Kuznetsova (RUS) 7-6 (7/4), 2-6, 6-3