Button shaves eight tenths off his team-mate's time and leaps to the top of the timesheets.
Everyone after Ericsson yet to set a time.
@FlyingFinn: Absolutely, a very good chance, especially as he was overlooked for that seat in favour of Verstappen.
Vettel showing no sign of a huge improvement for Red Bull, with his second timed lap only putting him sixth.
Bottas responds to Button's last time with a 1:42.669 but Button has just gone purple through the first sector.
Only Ricciardo and Massa yet to venture out on track at all in this session
. Other than Gutierrez, every other man is on the circuit.
@BhanuPrasad: Possibly, but also we don't know what everyone is running this weekend. McLaren, like all the teams, will have brought an aero package to this grand prix.
Button goes purple in all three sectors and reclaims top spot.
Kvyat has jumped into P3, with Hulkenberg also ahead of Magnussen. Kvyat gets congratulated on his lap but tells Toro Rosso his car feels "strange".
@Vinay: Nope, nothing has been confirmed. It's not even been confirmed where Vettel is going yet.
@ForzaJules: Yes, about a million.
All times so far are on mediums.
@DonovanKimiFan: No idea. Hard to judge when a driver is so young. Need to see how he does in other junior categories as he gets older before knowing whether he has the potential for F1.
All the teams will bring upgrades to every race. They don't tend to share the specifics with the media, however, for obvious reasons.
You could argue that, yes. Has he overtaken Hamilton yet this season? I don't think he has.
@BhanuPrasad: We don't know the second driver yet, but that's definitely an option.
Rosberg edges in front of Button with his first significant timed lap, a 1:41.882 putting him top. Hamilton slots into P3, four tenths down on Button in second.
Ricciardo's first lap only puts him into 13th, a 1:44.427. Massa has just joined the track so we should be seeing a timed lap from him soon.
@Phil,Maidenhead: You would certainly expect them to be more competitive than they have been with Renault. Button going elsewhere is a big unknown, at this stage in his career I don't know whether other teams would take him on when there are younger drivers around.
Hamilton now leaps into P1 with a 1:41.750.
Kvyat looking really handy around here. He's 0.808s down on Hamilton.
Grosjean reports a potential problem with his rear suspension.
That's true, but if they brought things to Suzuka they can bring them here, I believe. So there might be unused parts on the cars here.