(CNN) -- World champion Jorge Lorenzo may have thought new teammate Valentino Rossi would be his biggest threat of the new MotoGP season, but a surprise name will be at the head of the grid for Saturday's revamped final qualifying session in Qatar.
Rookie Marc Marquez, making his debut for Repsol Honda following the retirement of Casey Stoner and the departure of Andrea Dovizioso, snatched top spot from Lorenzo's Yamaha by just one-thousandth of a second in Friday's third practice.
"Practice today went pretty well -- better than expected," Marquez said. "I was very comfortable on the bike and this is the important thing.
"What we are missing is a bit of pace and consistency. We will have to make the most of the 30 minutes that we have before qualifying tomorrow to improve those points."
Under new rules for motorcycling's elite class, the top 10 riders automatically go through to "Q2" to decide the leading start positions for Sunday's opening race, while in the earlier "Q1" the rest will fight for the remaining two spots to take part the pole position shootout.
"It's separated qualifying, so that the fastest group runs together and the slowest group runs together," race director Mike Webb said.
"It's one thing for the show, and the other really big reason is for the safety of the riders; each rider group will get a clear race track and be better able to do their best lap time."
Splitting the sessions will also give the sponsors of smaller teams more television exposure, the MotoGP website said.
Most eyes will be watching seven-time world champion Rossi, who has returned to Yamaha after two unsuccessful seasons with Ducati.
"The practices were not so bad, but we are continuing to work for the race," Rossi said. "We still have to decide which tire to use; that will be very important for Sunday."
The Italian earned fourth place in the practice sessions, behind Britain's Cal Crutchlow on a Monster Yamaha Tech 3.
Compatriot Dovizioso, his replacement at Ducati, claimed sixth place ahead of last season's championship runnerup Dani Pedrosa -- who was outshone by his new Honda colleague Marquez.
Another Spanish rider, Alvaro Bautista, was seventh for Honda Gresini while America's 2006 world champion Nicky Hayden was eighth on the second Ducati ahead of British rookie Bradley Smith on the other Tech 3 and Germany's Stefan Bradl on an LCR Honda.
The 20-year-old Marquez has moved up to the top division after winning the Moto2 title last year, and the 125cc class in 2010.
With two-time world champion Stoner quitting last season after becoming disillusioned with the sport, there is a gap for Marquez to make his name.
However, he will have to show he can be as consistent as Lorenzo, who last season finished in the top two for 16 of 18 races -- with two retirements -- as he claimed his second title in three years.
"I'm very happy with the changes we made on the bike because it improved a lot," Lorenzo said. "I think we can still improve the bike more tomorrow.
"We still haven't decided which chassis is better; today it is the new one, yesterday the old one. I'm very curious to see how the qualifying goes with the new formula -- we will just be concentrating on doing four fast laps and the maximum performance we can get."
Before Saturday's two qualifying sessions, there will be one last practice run for the riders.
"We'll use the first three practices to get the right setups and then probably use the last free practice to do a long run, just to check the race situation," Lorenzo's crew chief Ramon Forcada said on the MotoGP website.
"It's not exactly the race distance, but half an hour should be enough -- and then we'll prepare for the time attack!"