Sweden's Robin Soederling dumped top seed Nikolay Davydenko out of the opening round of the Marseille Open 3-6, 6-4, 6-1 on Wednesday.
Spaniards David Ferrer and Juan Carlos Ferrero also suffered first round shocks at the Valencia Open on Tuesday.
Top seed Nikolay Davydenko and third seed Andy Murray reached the quarter-finals of $1.5 million Qatar Open in contrasting style in Doha.
Top seed Nikolay Davydenko beat defending champion Juan Monaco to take the Poertschach International title 6-2 2-6 6-2 on Saturday, storming back after an injury troubled him in the second set.
Top seeds Nikolay Davydenko and Juan Monaco battled through two matches each to reach the semi-finals in Poertschach.
Defending champion Davydenko, the top seed, struggled to keep pace with Argentina's Juan Monaco and slumped to a 6-2, 6-7, 6-4 defeat at the Poertschach International.
Top seed Nikolay Davydenko of Russia and second-seeded Croatian Ivan Ljubicic progressed into the second round of the $1 million Qatar Open in contrasting fashions on Tuesday.
Nikolay Davydenko won the Sony Ericsson title with a 6-4, 6-2 victory over Spain's second-seeded Rafael Nadal.
Fourth seed Nikolay Davydenko threw away a two-set lead before going down 4-6, 2-6, 6-2, 6-2, 6-4 to Croatian Ivan Ljubicic in the third round of the French Open on Saturday. Ljubicic, seeded 28th, will next face France's Gael Monfils, who beat Austrian Juergen Melzer.
Nikolay Davydenko will meet Juan Monaco in the final of the ATP tournament in Poertschach on Saturday.
The world number one was pushed by the Russian but survived to book his place in the last four of the Australian Open against German Nicolas Kiefer.
The fifth seed became the first major casualty at the Cincinnati Masters, losing in the opening round.
The unseeded Thai will face Italian David Sanguinetti, who upset number 31 Carlos Moya, in the second round at the US Open.
Serbian teenager Novak Djokovic beat Spanish qualifier Santiago Ventura 6-2, 6-2 to enter the quarterfinals.
Top seed Nikolay Davydenko tumbled out of the St Petersburg Open in the second round, going down to Croatian qualifier Marin Cilic.
The third seeded Russian will play will play Germany's Tommy Haas for a place in the semi-finals.
Russian second seed Nikolay Davydenko easily overcame a potentially tough challenger in Spaniard Feliciano Lopez to reach the second round of the World Indoor Tournament with a 6-4, 6-2 win on Wednesday.
Germany's Benjamin Becker caused the biggest upset at Wimbledon so far on Tuesday by knocking out fourth-seeded Russian Nikolay Davydenko 6-4, 6-4, 6-4.
They were beaten by Lee Hyung-Taik and Paradorn Srichaphan respectively in the quarter-finals of the China Open.
Russia's Elena Dementieva gave herself an early birthday present when she rallied after dropping the first set to beat Serena Williams 5-7 6-1 6-1 and win her maiden Kremlin Cup title on Sunday.
Swede Robin Soderling built on the momentum that allowed him to beat Rafael Nadal and reached the French Open semi-finals on Tuesday with a 6-1, 6-3, 6-1 drubbing of Russian 10th seed Nikolay Davydenko.
Fourth seed Nikolay Davydenko overcame an early fright to beat France's Florent Serra 6-7, 6-4, 6-1 on Tuesday in an error-strewn first-round battle at the Dubai Championships.
Marat Safin, just a few weeks short of retirement, knocked out top seed Nikolay Davydenko 4-6, 6-4, 6-2 in a high-profile first-round tie between the two Russians at the Kremlin Cup on Wednesday.
Nikolay Davydenko of Russia beat Italy's Andreas Seppi 6-1, 6-2 in the second round of the Hamburg Masters
Russia's Nikolay Davydenko became the highest seed to exit the Pacific Life Open but three-times champion Roger Federer barely broke sweat in reaching the fourth round in Indian Wells on Tuesday. Crowd favourite and top seed Federer, back in action at Indian Wells after recovering from illness, outclassed Frenchman Nicholas Mahut in only 53 minutes.
The Russian received a warning from the umpire for not trying hard enough during his loss to Croatian qualifier Marin Cilic at the St Petersburg Open.
Russian top seed Nikolay Davydenko will start favourite in the singles while Leander Paes and Mahesh Bhupathi will shoulder local hopes in doubles as the US $450,000 Chennai Open, featuring one of the strongest singles field this year, kicks off in Chennai on Monday. The crowd will see a range of international stars including seven top-50 players competing for the top honour with Swiss Olympic champion Stanislas Wawrinka also throwing his hat in the ring.
World number one Roger Federer recovered from a set down to beat unseeded German Denis Gremelmayr 2-6, 7-5, 6-1 on Saturday to reach his first final of the year at the Estoril Open. He will now face the number two seed Nikolay Davydenko of Russia, who beat France's Florent Serra 6-2, 6-2 in the other semi-final.
Nikolay Davydenko and David Ferrer, seeded two and three respectively, were knocked out of the World Indoor Tournament on Thursday.
Russian Nikolay Davydenko clinched his first title of the season on Sunday when he crushed Frenchman Paul-Henri Mathieu 6-4, 6-2 to win the German Open.
The win gave the Russian his third title of the year.
World number one Rafael Nadal beat Russian third seed Nikolay Davydenko 6-3, 6-2 in the semi-finals of the Barcelona Open on Saturday to stay on course for a fifth successive title at the Catalan event. In a repeat of last year's final, the Spanish top seed will play compatriot David Ferrer on Sunday after the fourth seed came back from a set down to defeat fifth-seeded Chilean Fernando Gonzalez 2-6, 6-2, 7-6.
Marcos beat holder Nikolay Davydenko 6-2, 6-2 in the third round of the Paris Masters Series.
World No 2 Rafael Nadal will face fourth-seeded Russian Nikolay Davydenko in the Sony Ericsson Open final after semi-final victories on Friday. The Spaniard, who reeled off the last 12 points of the match, beat Czech Tomas Berdych 7-6, 6-2 in windy conditions, while Davydenko beat Andy Roddick of the United States by the same scoreline.
The world number two launched his campaign for a third successive Rome Masters title with a below-par win over Italian wild card Daniele Bracciali.
Top seed Nikolay Davydenko of Russia on Wednesday pulled out of the Chennai Open ATP tournament and Australian Open Grand Slam owing to an injury to the heel of his left foot.