Fernando Alonso led the two Mercedes in the opening practice session for this weekend's Singapore Grand Prix.
The Spaniard posted a 1:49.056 to pip the Silver Arrows by a just over a tenth of a second as the two Red Bulls and Jean-Eric Vergne completed the top six.
The big story heading into the weekend is the clamping down on certain radio messages. After meetings on Thursday, further alterations were made with advice on the settings of the power unit re-allowed, however, assessing the impact of the banning of the other instructions was keenly followed during the session.
In short, the effect is rather minimal. Information regarding brake bias and suggestions as to how to deal with some situations remained fairly common with just those questions regarding lap times of competitors the most noticeable change.
In the opening session, however, most drivers and teams were merely easing their way into the weekend, assessing the racetrack and the basic setup. So while the impact was small in the first 90 minutes, when drivers get down to serious race preparation later on I think the scale of the changes will be fully known.
As is the case with the opening practice at most circuits, conditions were not very representative compared to how they will be later in the weekend.
Indeed, for a night race, the session started in the twilight therefore track temperatures were higher even if the ambient figures remain fairly constant regardless of what time it is.
Also, for a city that prides itself on being one of the cleanest in the world, even Singapore's streets are dusty when it comes to the level of grip on the racetrack.
Track evolution is among the highest on the calendar as the lap-times drop some four or more seconds from opening practice to the end of qualifying.
Despite Alonso leading the timing screens, it seems already Mercedes do have the edge over their rivals this weekend.
Some believed that their recent dominance and the higher downforce needed in Singapore would give Red Bull a chance, and while they already look set as the 'best of the rest', the two Silver Arrows held over half a second advantage without breaking too much sweat.
Among the drivers, well its as close as most predicted with Lewis Hamilton under three-hundredths of a second quicker than Nico Rosberg as the pair traded places all session long.
Toro Rosso strong
Despite having a few issues during the session, it seem Toro Rosso could be a threat to the midfield pack this weekend.
Vergne and Daniil Kvyat both made the top 10 with the Frenchman sixth and the Russian ninth.
The junior Red Bull team traditionally are strong on the lower grip circuits and while Williams continued their trend of easing into a weekend with both cars only 13th and 15th respectively, teams like Force India and McLaren may have to watch out.
After an eventful two weeks off the track at Ferrari, it appears they may join Red Bull in being a greater threat on it this weekend.
Though they have run lighter fuel than their rivals in practice throughout much of the year, Kimi Raikkonen's seventh place may be a greater indicator as to where the Prancing Horse is in the pecking order.
Certainly, it appears that we have a three-way battle between Red Bull, Ferrari and Williams for the final podium place, however, with Marina Bay a very fuel-hungry circuit, that could prove their downfall in the race on Sunday.
As is expected, the long lap with so many corners is generating a higher delta time between those at the front and those at the back.
Six seconds was the gap between Alonso in first to Max Chilton in 22nd and indeed based on the opening session, the two slower teams may struggle to match their nearest rivals this weekend.
Over a second was the gap between Romain Grosjean and Jules Bianchi, however the Frenchman did appear to lose some running as he only completed 15 laps.
Excluding the Williams, the two groups of the midfield appear wider than usual as well.
Half a second was the gap between Nico Hulkenberg's Force India - the slowest of the leading group of midfield teams - and Pastor Maldonado at the head of the Lotus/ Sauber battle.
With quite a few patterns already developing we will get a clearer view in the second session later today as the drivers enjoy the conditions expected for the race and the red-striped super-soft tyres are used for the first time as well.
The impact of the radio restrictions will also be more noticeable as the teams complete full qualifying and race simulations ahead of the main action that begins on Saturday.
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