PARIS: Battling Rafael Nadal moved into the Paris Masters quarter-finals with a 6-3, 3-6, 7-5 win over Tommy Robredo underlining his threat to unseat Roger Federer as World No 1 by the end of the season. With Federer a shock loser to Frenchman Julien Benneteau, a win for Nadal in Sunday's final would leave him just 305 points adrift of his arch rival with the season-ending ATP World Tour Finals to come in London later this month. Nadal ended Federer's long reign as World No 1 after winning the Beijing Olympics last year, but Federer bounced back to regain the top spot in July after winning both the French Open and Wimbledon titles. Joining Federer on the sidelines though was fourth seed Andy Murray who found two matches in one day too much to handle as he lost 1-6, 6-3, 6-4 to Radek Stepanek of the Czech Republic. The Scot, who won a season-best sixth title in Valencia on Sunday, was taken to 1:45 am the night before in defeating James Blake 6-3, 6-7 (5/7), 7-6 (7/4). Nikolay Davydenko meanwhile became the seventh player to qualify for the eight-man London Tour Finals despite losing 6-3, 3-6, 6-4 to Sweden's Robin Soderling in another third round match. Placed seventh in the standings coming into Paris, the loss briefly left the Russian at the mercy of the four other players in with a chance of playing in London. But then Spain's Fernando Verdasco, who was holding on to the eighth and final slot, lost 3-6, 6-3, 6-4 to Marin Cilic of Croatia. His defeat meant that Davydenko was assured of finishing the week no lower than eighth which stamped his ticket for London. Verdasco was left having to sweat it out while keeping an eye on the progress of the three other potential finalists — Soderling, Jo-Wilfried Tsonga, who reached the last eight here with a 6-2, 6-3 win over French compatriot Gilles Simon, — and Chile's Fernando Gonzalez. Gonzalez though saw his hopes dashed in the final match of the day when he let slip seven match points in the second set to US Open champion Juan Martin del Potro of Argentina before abandoning at one set all 6-7 (6/8), 7-6 (8/6). Next up for him, with a place in the semi-finals at stake, will be third seed Novak Djokovic, who cruised past French qualifier Arnaud Clement 6-2, 6-2 in 75 minutes. The 2008 Australian Open champion from Serbia, last year's Tour Finals winner, is seeking to lift back-to-back titles following his win in Basel last week where he beat Roger Federer in the final. Benneteau failed to carry his form into Thursday losing 6-4, 6-3 to compatriot Gael Monfils.