- Michael Schumacher sets the pace in opening practice session of 2012 Formula One season
- Mercedes' veteran German driver has not been fastest in practice since returning in 2010
- Double world champion Sebastian Vettel down in 10th place, with Mark Webber 11th
- The season begins with the Australian Grand Prix Sunday, with qualifying Saturday
Michael Schumacher has struggled to repeat his past Formula One glories since returning from retirement two years ago, but the seven-time world champion left his heir apparent Sebastian Vettel trailing as the 2012 season got off to a wet start in Australia on Friday.
The 43-year-old had not even topped a practice session in his comeback with the Mercedes team, but he laid that to rest in Melbourne by being fastest around a rain-soaked circuit with a time of one minute 29.183 seconds in the second session.
Vettel, seeking to join Schumacher and 1950s legend Juan Manuel Fangio as the only drivers to win three successive world championships, languished in the middle of the pack.
F1's youngest double world champion was down in 10th place, more than three seconds adrift of the pace set by his fellow German.
McLaren's former world champions Jenson Button and Lewis Hamilton had been first and second on the timesheets in the day's earlier session.
Mercedes have been tipped by many to challenge the dominant trio of Red Bull, McLaren and Ferrari this season, and Schumacher was excited by the German team's results in the year's opening session.
"Today was a nice start into a hopefully exciting season, and certainly two promising sessions for us," the former Ferrari star told F1's official website.
"However, I would not go so far as to speak about being confident, as the weather conditions were too mixed to gain a clear picture.
"We know what Friday sessions are for and don't know what fuel loads others were running. On the other hand, it is good to see that we were competitive in different circumstances today and that the car provides good handling -- I just feel it."
Vettel rued the wet conditions and warned that Red Bull must improve ahead of Sunday's season-opening race.
"I think obviously with the conditions it's difficult to get a lot of running, but it was the same for all of us," the 24-year-old said. "The little time we had in the car this afternoon was okay, but now we have to find the balance and learn a bit more about the car.
"The important thing now is to make a step overnight and go from there. Track time is important when the car is still young."
Another German, Nico Hulkenberg, was in impressive form in his first session in the sport since leaving Williams at the end of the 2010 season. The Force India driver was second fastest in the second session ahead of Sauber's Sergio Perez.
Italian team Ferrari's preseason was dominated by questions over their performance, but Spanish two-time world champion Fernando had a solid second session, posting the fourth-fastest time.
"We will try to do our best, putting together the best elements we have tried in the past weeks, including a few details we brought here," the 30-year-old said.
"But if I was to give some sort of opinion on the day, I would say it's been positive. We did the important things, the balance is good and the car responds well to changes."
Red Bull's second driver Mark Webber was 11th ahead of his home grand prix, leading Button and 2008 title winner Hamilton in 15th and 16th respectively.
Button, the 2009 world champion with Brawn GP, warned against reading too much into practice results.
"Even though it doesn't mean too much, it's always nice to start the season with the quickest time of the day," the 32-year-old said.
"There are still a few areas where I think we can improve, and we didn't get as many laps in today as we'd have liked, but it's been a positive day."