Tuesday at Sepang saw double MotoGP champion Casey Stoner ride alongside the full-time MotoGP field for the first time since retirement at the end of 2012.

A few days earlier, the 30-year-old Australian had made an impressive return to Ducati - the factory for which he won his first world title in 2007 - during a private test at the Malaysian circuit.

Stoner finished Tuesday's official test in ninth position, using last year's GP15, having reached a peak of eighth during the day. But lap times were distorted by Loris Baz's huge morning accident, which resulted in the soft rear tyre being removed from use.

Stoner's 2m 1.103s was set on the 37th of his 45 laps, using the hard rear. It put him 1.008s behind Pramac Ducati pace setter Danilo Petrucci (soft rear) and 0.948s from the fastest hard tyre lap by Yamaha's world champion Jorge Lorenzo.

But Stoner looked to be faster than the other Ducati riders on the hard tyre.

Petrucci, for example, did not break the 2m 2s barrier after his morning flyer, with team-mate Scott Redding (7th) setting a 2m 1.8s in the closing stages of the day.

Factory stars Andrea Iannone (8th) and Andrea Dovizioso (14th) set a best of 2m 1.6s and 2m 2.4s respectively in the afternoon. Iannone and Dovizioso were starting work on the new GP16, but either way it was - as many expected - another impressive performance by Stoner, who insists he has no need to chase lap times on the soft tyre anyway.

"It was nice to be back on the track at the same time as the other riders, more just for the fact that we are testing at the same time, so we're not testing on a dirty track," said Stoner, speaking in the Sepang paddock. "We had the same track conditions, so we're getting the same feedback as the other guys in the team, and this is important to move the bike forward.

"It's hard work, especially physically. But it was very nice to see that every setting, every change that we made, some progress and we understood exactly what the bike was doing. I started to get more comfortable with the Michelin tyres, so I started to understand what to expect from them, and where you can kind of go to the limits at some points, especially in the braking zone.

"I think more or less everyone is having the same kind of issues getting accustomed to them, but a couple steps we did today, especially with the last tyres, we really started to make some progress.

"I'm not looking to put on a new soft tyre and try to get a lap time. This is something that when you're competing you get the urge to do, to crush the competition. I don't need to at this point, so it's literally getting as much data as we can.

"It's very clear with every step we make what direction we need to go in. Many of the comments between myself and both Andreas seem to be very similar, so we are working towards one goal."

Asked about the strong overall Ducati performance, Stoner joked:

"Clearly it's already because of my testing! No, second day on the bike for me, and already they had a good package. I think we saw at the end of last season that the Ducati riders seemed to be adapting quite well with the electronics, but not only that, with the Michelin tyres.

"This was just another step from there. Everybody was able to take some really good pace out in the morning in cold track conditions, but seem to be holding the lap times during the day. This is very positive and good to see."

Since his retirement, Stoner had taken part in occasional MotoGP tests for Honda before returning to Ducati for as a test rider and brand ambassador at the start of 2016.

Unlike when Stoner was racing for Ducati, the Desmosedici now has a conventional aluminium frame, as used by the other MotoGP manufacturers. So what are the similarities to the Honda?

"Of course, you're never going to get two bikes very similar. There are some characteristics, mainly on the brakes, that I would compare the two, but other than that, they needed to be ridden completely differently," Stoner replied.

"I needed to learn that on the first day, to take a bit different lines, and a little bit different approach to what I normally would. But in general every bike has its strong points, and we just need to find these, and then try and work with them.

"The weak points that we felt, I think we made some progress on them today. We're trying a lot of different things and every time we went out, we generally made a step forward. And if we made a step back we generally found at least one positive to take from it. So it's been good feedback."

Having spent Monday watching trackside, Stoner was also asked for his observations on the 2016 RC213V, which is struggling to adapt to the new single ECU software and tame it's aggressive engine character.

"The Honda, they don't seem to be in their normal comfort zone, they're not adapting too well," Stoner confirmed. "I don't know if it's the new engine, the new electronics or both. But for sure they don't seem to be in that zone of comfort. There's still a long way to go, it's just the first test of the season, so there's still plenty of time. I'm sure they will find something."

Although it was initially planned that Stoner would ride for just one day this week, Ducati has confirmed he will be back on track for Wednesday's final day. The #27 is set to continue with the GP15, before making the switch to the new bike.

"We don't really want to overcomplicate things, and the [race] riders want to do their testing with it first. Maybe I'll get an opportunity in the future, but it's better just for me to get accustomed with everything, start to learn a little bit of the progression, and when we find where we want to be with the GP15 - not necessarily where the limit is but can feel we can't go too much further - then maybe we will progress to the next version, and see how it works. But there's a lot of time between now and then."

Meanwhile, Stoner again played down suggestions he might make a wild-card entry this season.

"It's nice to be back on track with them today, mainly to get the data, but I think I'm still going to enjoy standing on the side of the track watching the race rather than being out there."

Later in the evening Stoner was seen chatting in the paddock with HRC vice president Shuhei Nakamoto, underlining that they had parted on good terms.