* Hamilton wins in Canada for McLaren
* Briton is seventh different winner in seven races
* Grosjean second for Lotus in career best (Adds detail, byline)
MONTREAL, June 10 (Reuters) - McLaren's Lewis Hamilton stormed to a Canadian Grand Prix victory on Sunday to become a magnificent seventh winner in seven Formula One races this season and seize the championship lead.
The Briton had to mount a ferocious charge after his second pitstop, banging in a series of fastest laps to reel in Red Bull's reigning world champion Sebastian Vettel and Ferrari's Fernando Alonso.
Frenchman Romain Grosjean was second in a Lotus, a career bost, with Mexican Sergio Perez third in a Sauber after overtaking Alonso - a driver he may end up partnering next season if he continues to impress.
It was Hamilton's third win in Montreal, an island circuit where he took his first grand prix triumph in 2007, in five attempts.
The 2008 champion, who also stood on top of the podium in Canada in 2010, had his most worrying moments in the two pitstops - McLaren's weak point this season - but on the track he was unstoppable.
"What a great feeling, this is where I won my first Grand Prix and I knew today would be a tough, tough race but I loved every single minute of it," said Hamilton, who now has 88 points to Alonso's 86 and Vettel's 85.
Brandishing the British flag as he stepped out of the car after a gripping finale, he hugged his mechanics while girlfriend Nicole Scherzinger kissed his visor.
"It's been five years since I won here the first time but it feels just as good. It feels great to be on the top step, we never take it for granted," he said.
"This for me feels like one of the very best races I have had for a long time."
Vettel had started from pole, just like last year, and led the early part of the 70 lap race but lost pace over the final laps to finish fourth in a grand prix that his Red Bull team have yet to win.
Spaniard Alonso, bidding to give resurgent Ferrari a victory on the 30th anniversary of the tragic death of former-Ferrari great Gilles Villeneuve but struggling on worn tyres at the finish, had to settle for fifth.
(Editing by Alan Baldwin)