Nico Rosberg edges out teammate as Mercedes takes over front row for the Spanish Grand Prix Mercedes driver Nico Rosberg gives the thumbs up after grabbing pole position for tonight's Spanish Grand Prix at the Catalunya racetrack near Barcelona. Germany's Nico Rosberg en route to recording the fastest time during the final qualifying session. NICO Rosberg secured his third career pole position as Mercedes completed a hat-trick of qualifying successes - and then warned that he is worried his tyres will let him down in tonight's Spanish Grand Prix. The 27-year-old German led the way as his team locked out the front row of the grid but he was immediately concerned afterwards that he does not endure a repeat of his problems at last month's Bahrain Grand Prix where he limped home ninth. Rosberg clocked a dazzling best lap time of 1min 20.718sec to outpace his nearest rival and Mercedes teammate Lewis Hamilton by two-10ths of a second. After poles secured by Hamilton in China and Rosberg in Bahrain, this was a magnificent treble top for the resurgent Mercedes outfit as it outclassed its rivals at the Circuit de Catalunya. Defending triple world champion Sebastian Vettel gave his best for Red Bull to qualify third ahead of Kimi Raikkonen for Lotus, local hero and two-time champion Fernando Alonso and his Ferrari teammate Felipe Massa. Times started to drop after the medium tyres came out late in the session, and Massa took advantage to clock a best time of 1min 21.901sec in mostly sunny conditions. Red Bull driver Mark Webber was third quickest, just in front of Romain Grosjean for Lotus. Three-time Formula One defending champion Sebastian Vettel was fifth for Red Bull, one place ahead of two-time F1 winner Fernando Alonso of Ferrari. Australian Daniel Ricciardo was 18th. The top six drivers were separated by only 0.353sec, suggesting qualifying will be close. McLaren's struggles show no signs of ending, however, with Jenson Button and teammate Sergio Perez outside of the top 10 places for the second straight day. Qualifying is later tonight. The race tomorrow. Massa has started every race in the top five this season, but Ferrari is looking for its drivers to find extra speed in qualifying following three frustrating seasons to increase the pressure on Red Bull. The closest Ferrari has been to pole position this season was when Massa qualified second at the Malaysian GP in March. Teammate Fernando Alonso has started the past three races from third spot on the grid, and he will be hoping for a higher position in front of his home fans on the Circuit de Catalunya. Raikkonen, who won the season-opening race in Australia despite starting from seventh spot, will be looking for a third consecutive podium finish. Grosjean has had a frustrating start to the campaign, although his form picked up with a third-place in Bahrain. Mercedes has been fast but lacking durability so far this season, but Lewis Hamilton and Nico Rosberg stayed on longer runs than any other driver in completing 50 laps between them. Having set the early pace on hard tyres, Vettel will need to pick up the pace in the afternoon to earn a third pole of the season after starting top of the grid in the first two races. The German has won twice so far this campaign. Following on from yesterday's two underwhelming practice sessions, McLaren's prospects still look gloomy. Button was 1.25 seconds off the pace in 12th place on Saturday, while Perez was 1.472 back in 14th.