He then failed to win back-to-back matches in his next four tournaments until the 2010 Western & Southern Financial Group Masters, where he defeated Robby Ginepri and David Ferrer, both in three sets, before falling to Roger Federer in the quarterfinals, 4–6, 5–7. He also reached the quarterfinals of the 2010 China Open, but failed to defend his title in the Shanghai Rolex Masters and fell out the top 10 for the first time in over a year. He then reached three consecutive quarterfinals in the 2010 Open Sud de France, 2010 Valencia Open 500, and 2010 BNP Paribas Masters. Davydenko did not qualify for the Barclays ATP World Tour Finals. This was the first time he did not qualify since qualifying for the first time in 2005. He also dropped out of the top 20 for the first time in over years. 2011–2014 : Decline 2011 2011 saw a decline in Davydenko's form. His first appearance was in the Qatar Open, where he defeated Rafael Nadal in the semifinals, but he fell in the final to Roger Federer. At the 2011 Australian Open he was defeated by unseeded Florian Mayer in four sets, 3–6, 6–4, 6–7, 4–6. He then fell in the opening rounds of 2011 ABN AMRO World Tennis Tournament and 2011 Open 13 to Frenchmen Michaël Llodra and Gilles Simon, respectively. In the 2011 Dubai Tennis Championships and 2011 BNP Paribas Open, he fell in the opening and second rounds to Tomáš Berdych and Stanislas Wawrinka, respectively. In the next two Masters 1000, he fell in the first round of the 2011 Sony Ericsson Open and 2011 Monte-Carlo Rolex Masters. He then earned his first back-to-back wins since Doha in the 2011 Barcelona Open Banco Sabadell, but fell in the third round to Nicolás Almagro, 6–7, 3–6. Then, at the 2011 BMW Open tournament, he started slowly but progressively found some good form, which allowed him to eventually win the final, 6–3, 3–6, 6–1, against Florian Mayer. This was his 21st ATP title, and it meant that he had won at least one ATP-tour title for nine straight years and returned him back into the top 30 in the rankings. This was, however, his only final of the year and he failed to progress past the third round in any Grand Slam or Masters tournament, although his defeat at the US Open, came to world number one