Rafael Nadal lines up on Wednesday against Australian Marinko Matosevic at the Monte Carlo Masters as the Spaniard begins his campaign for a record ninth straight trophy at the iconic venue.
Nadal's opponent Matosevic faces the toughest ask in tennis after winning his first match on clay in almost a year to open Tuesday with a 7-5, 6-3 success over Fernando Verdasco.
Top seed Novak Djokovic meanwhile informed tournament director Zeljko Franulovic that he would be fit to make his start in the second round after a bye.
Djokovic has been putting in training and tests on his injured right ankle over the past few days. He will begin against Russian Mikhail Youzhny, who stands a respectable 3-4 in their career series.
Wednesday's line-up features Nadal, Djokovic and second seed Andy Murray, whose profile has been the quietest of the major contenders so far.
Matosevic, the number 54 in the world, won't have time to celebrate his upset of Spain's former ace Verdasco.
Instead, he will become just the first obstacle placed in the path of Nadal, winner of his last 42 matches here at the Country Club overlooking the Mediterranean.
Matosevic sprang a surprise on Verdasco, the one-time clay powerhouse and 2010 runner-up here to Nadal, going through to the second round in a struggle as his Spanish opponent fought back at the end in the one-hour, 51-minute contest.
Matosevic saved nine of the dozen break points he faced while breaking the 31st-ranked Verdasco on five occasions.
The Australian last won a clay match in the first round of French Open qualifying last May after earning his last ATP win on the surface in Munich a few weeks earlier.
In other first-round matches on a perfect, sunny day, Spain's 10th seed Nicolas Almagro came back against Belgian David Goffin 2-6, 6-1, 6-3, while Swiss 13th seed Stanislas Wawrinka beat Denis Istomin of Uzbekistan 6-3, 7-5.
Argentine 14th seed Juan Monaco defeated Slovak Martin Klizan 6-4, 6-0, but French showman Gael Monfils lost to Albert Montanes 6-2, 2-6, 6-4.
In the second round, Argentine wild card and fifth seed Juan Martin del Potro survived an early scare from Alexandr Dolgopolov, with the South American finally posting a 1-6, 6-4, 6-3 win and securing his first career victory in Monte Carlo after last playing in 2009.
French sixth seed Jo-Wilfried Tsonga beat Russian Nikolay Davydenko 7-6 (7/3), 6-2 while compatriot and number seven Richard Gasquet struggled before containing countryman Benoit Paire 6-1, 3-6, 6-1.
Bulgarian Grigor Dimitrov upset eighth seed Janko Tipsarevic 7-6 (7/3), 6-1, with the Serb double-faulting on a set point in the opening set and tweeting that he is now taking a few days off.