(CNN)Lewis Hamilton celebrated signing his new Mercedes contract by claiming the first pole position of his Formula One career at his favorite track on Saturday.
Monaco Grand Prix: Hamilton 'so happy' after F1 career first
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The world champion will head the grid at Sunday's Monaco Grand Prix, denying teammate Nico Rosberg his third successive qualifying success at the testing street circuit.
The German converted those two poles into race victories, and Hamilton will be seeking to emulate him with his first win in the principality since 2008 -- the year he won his maiden F1 drivers' title.
"I can't express to you how happy I am," said Hamilton, who signed a three-year deal with the German manufacturer on Wednesday to end speculation about his future.
"It was not the easiest session. There were a lot of things that throw you off your rhythm and I did not have that rhythm until the last couple of laps.
"I am very, very happy. This track is so hard. It is difficult to express how difficult it is. In our session we had some problem with tires and traffic -- it was not easy so it makes it even more special.
"We had some really bad laps, so it was great."
Hamilton clocked a best time of one minute 15.098 seconds -- almost a second faster than Rosberg's 2014 pole, and 0.342s quicker than his rival this time as he posted the 43rd pole of his career.
He is now just two behind third-placed Sebastian Vettel in the all-time list, though they are both a long way off Michael Schumacher's leading 68.
Last year, Hamilton complained that Rosberg intentionally ruined his flying lap as tensions between them escalated -- though his rival was cleared by stewards. This time Hamilton was first out of the pits as agreed by their team.
Rosberg, who is 20 points behind leader Hamilton in the championship after five of 19 races, was quickest in Saturday's first two sessions but made errors in Q3 as conditions cooled and rain fell, locking up twice.
"I didn't have a good weekend so far -- I lost touch before the end. I knew Lewis was going quickly and it didn't work out," he told reporters.
"I could have improved -- we changed the balance as I was suffering understeer, and I was confident it was going to come my way. But it didn't."
Hamilton matched Vettel's run of 14 successive races on the front row -- the best by any current driver.
The German will start third on the grid for Ferrari, having gone 0.75 seconds slower than the Englishman.
"I am generally happy with the result but it was a bit too cool for most people and we were struggling with warming up the tires," said the four-time world champion, who won at Monaco in 2011 for Red Bull.
"It is a shame the sun was hiding behind the clouds but overall it was a good session and our aim now is to have a good race tomorrow and try to split the Mercedes."
Vettel's teammate Kimi Raikkonen -- who won at Monaco 10 years ago with McLaren -- was sixth behind the improved Red Bull duo of Daniel Ricciardo and Daniil Kvyat despite hitting a wall.
Force India's Sergio Perez qualified seventh, with Toro Rosso rookies Carlos Sainz Jnr. and Max Verstappen eighth and 10th fastest. However, Sainz will have to start from the pit lane after failing to attend the weighbridge.
Lotus driver Pastor Maldonado was therefore promoted to eighth, but teammate Romain Grosjean will be 15th after a five-place penalty for a gearbox replacement.
McLaren's former world champions Fernando Alonso and Jenson Button once again missed Q3, and will start 13th and 10th respectively following Grosjean and Sainz's demotions.
Williams also struggled, with Felipe Massa to start 12th and Valtteri Bottas 15th after missing Q2.