SEPANG, Malaysia - McLaren's Lewis Hamilton hogged the limelight on Friday by topping both practice sessions in a bid to ignite his championship victory charge at the Malaysian GP.The 2008 World champion, who has yet to win at Sepang, made 1min38.021 in the morning drive and again led the way on a stifling afternoon with 1min38.172.Michael Schumacher, whose Mercedes has drawn attention for its innovative "W-duct" rear wing, was 0.361 behind in the second session with McLaren's Jenson Button, the season's early points leader, in third.HAMILTON ON TOPSchumacher's team mate Nico Rosberg placed fourth with Toro Rosso's Daniel Ricciardo in fifth. Ferrari's Fernando Alonso was sixth ahead of Red Bull driver Mark Webber.Red Bull's Sebastian Vettel had a quiet afternoon and wound up 10th, 1.23s off Hamilton's pace.Stay with Wheels24 for the Formula 1 weekend.Vettel said: "There is still a lot to do. The tyres drop off (wear) quite quickly here, which is the same for all the drivers, but I think we are sliding quite a bit and I would like the car to be a bit more stable. We made a good step today, the potential is there, but we need to get to it."We will see what we can on Saturday."Hamilton qualified quickest during the season-opener in Australia, too, but had to settle for third at at the flag behind Button and Vettel, frustrating his bid to seize early control of the title race.On a typically hot, overcast afternoon with the temperature at 31 degrees, Hamilton was at the top of the pack with a time of 1min38.921 inside the first 20 minutes.Ricciardo turned heads as he bettered Hamilton's time by seven hundredths of a second, while Webber and Caterham's Heikki Kovalainen narrowly avoided touching wheels as they fought through a tight right-hander.Hamilton ran wide on his ninth lap but he came storming back to drop his time again to 1min38.617, despite locking a front wheel late in the lap.DISMAL HRTSchumacher briefly headed the field around the one-hour mark before Hamilton cut his mark by two-hundredths and then lopped it again to 1min38.172, a time that endured the last 20 minutes of the second practice.Force India's Paul di Resta finished 13th after a brake issue forced him wide early in the session and then a sideways slide which left him riding on the grass beside the track.HRT's Narain Karthikeyan, too slow in qualifying to even start in Australia, spun late in the session and ended second last.Despite concerns from rival teams, officials have raised no objections to Mercedes' rear wing, which channels air-flow to cut resistance on the nose when the drag reduction system overtaking aid is engaged.