(CNN) -

Lewis Hamilton might be in the midst of one of the fiercest Formula One battles of recent years but the Mercedes man is staying cool -- ice cool.

While Hamilton has just eight races remaining to secure a second world title, the 29-year-old took time out to brave the ALS ice bucket challenge.

But while some might have frozen with shock, Hamilton was in red-hot form during practice at Spa Francorchamps, Belgium, Friday.

The British driver, who trails teammate Nico Rosberg by 11 points in the standings, finished more than half-a-second clear of the field in the second practice session.

"It's great to be back in the car and it was feeling good out there today," Hamilton told reporters on the first day back after the mid-season break.

"The morning wasn't as strong, but it definitely improved in the afternoon. As always, we still have work to do tonight, but overall today was OK.

"It stayed dry throughout both sessions but the forecast is wet for tomorrow, so it was important to maximize track time as this may be our last dry running before the race.

"We've seen rain so often here in the past and that can really mix things up -- particularly when it's wet in places and dry in others.

"Your visor is almost level with the ground, so it's not like looking from above where you can see the different patches.

"That makes it really hard to pick out the areas where you can find grip, but it's also a lot of fun."

Hamilton set a fastest lap of one minute 49.189 seconds on the soft compound tires, with German Rosberg just behind on one minute 49.793 seconds.

Fernando Alonso, who finished 0.741 seconds behind Hamilton, was third ahead of Williams' Felipe Massa and Jenson Button in the McLaren.

Hamilton, whose five victories this season have taken him to 191 points, will start as favorite for pole position on Saturday but Rosberg is confident he can come out on top with adverse weather expected.

"As normal, it will be a long night analyzing everything that we learned today to really nail it tomorrow," Rosberg told reporters.

"The interesting challenge for this weekend is to find the right compromise between being quick over one lap and over a long distance in the race -- especially if it's wet tomorrow, with the predictions currently saying we will have mixed conditions."

Elsewhere, reigning world champion Sebastian Vettel was forced to miss the session after his Red Bull suffered engine failure.