Monte Carlo - Clay aces Stan Wawrinka and Rafael Nadal started their spring seasons in enviable form on Wednesday by booking spots in the third round of the Monte Carlo Masters.
Reigning Roland Garros champion Wawrinka notched up a 7-6 (7/2), 7-5 victory over Philipp Kohlschreiber.
Nadal, seeded fifth, emerged a 6-3, 6-3 winner over Briton Aljaz Bedene as the Spaniard tries to recover the form which saw him dominate clay for most of a decade.
But Bosnian Damir Dzumhur pulled off a huge upset with his defeat of Czech sixth seed Tomas Berdych 6-4, 6-7 (1/7), 6-3. It marked only the second career win for the 99th-ranked underdog over a top 10 opponent.
Number four Wawrinka, who also won the title at the seaside Monte Carlo Country Club over Roger Federer in 2014, will line up in the third round against French 15th seed Gilles Simon. Nadal will play Austrian Dominic Thiem, who fought back to defeat Japan's Taro Daniel 4-6, 6-2, 6-0.
"He's a really tough player," Wawrinka said of Simon. "It's going to be a good test for me to see where is my level. I will have to play already a really good match if I want to beat him."
The Swiss took 96 minutes to advance over Kohlschreiber, who fought off the Wawrinka attack as he saved 10 of 13 break points against his serve.
"It was a good first match on clay. It's never easy to find the rhythm and to play the perfect match. In general, I'm quite happy with the level already," Wawrinka said.
Wawrinka will be trying to build momentum on clay this spring as his May return date to the French Open draws closer.
Wawrinka finally finished with a break in the second set for 6-5 and claimed victory a game later on his first match point to take his record over Kohlschreiber to 4-0. It was Wawrinka's second defeat of the German this season after Dubai in February.
The 31-year-old Wawrinka is one of only four men to have disrupted the Big Four's trophy dominance of Masters 1000 titles since Monte Carlo 2010. Fifty of the last titles in the series have been won by either Novak Djokovic (23), Rafael Nadal (12), Roger Federer (8) or Andy Murray (7).
Wawrinka is part of an elite spoiler's list also comprising Robin Soderling (Paris-Bercy 2010), David Ferrer (Paris-Bercy 2012) and Jo-Wilfried Tsonga (Toronto 2014).
Elsewhere, French 16th seed Benoit Paire defeated Joao Sousa of Portugal 6-4, 6-3 to reach the third round at his second consecutive Masters event after Miami last month.