A massive downpour arrived mid-way through Q2, causing several delays to the final shootout for pole. When it did get underway, Hamilton moved to the front immediately with an imperious lap that would ultimately prove enough to secure pole.
It was mightily close however, as Vettel improved at the end to get within 0.074s of the lead Silver Arrows. His gain was Nico Rosberg’s loss: the German was unable to improve on his own flyer and had to settle for third. With Ferrari looking quick, and with the weather promising potential upsets, Mercedes may have a fight on their hands on Sunday.
Q1 got underway with a 70 percent chance of rain at some stage during the afternoon - the question being therefore whether qualifying would finish before the storms arrived.
Mediums were therefore the tyre of choice for many, as the field looked for banker laps. And as the sky darkened and thunderclaps boomed late in the session, Hamilton and Rosberg set the pace with 1m 39.269s and 1m 39.374s respectively on the mediums - although Vettel’s 1m 39.814s on the hards was ominous. That was later equalled by Sainz, on mediums.
A rash of late improvements finally saw Felipe Nasr as the first man not to get through to Q2, with 1m 41.308s in his Sauber. But that left him comfortably ahead of the McLarens. Jenson Button beat Fernando Alonso as the Spaniard’s final effort came up short; they lapped in 1m 41.636s and 1m 41.746s respectively.
Roberto Merhi made a brave effort to qualify in his Marussia, cutting down to 1m 46.677s despite a half spin, but team mate Will Stevens didn’t get out at all as fuel system problems from FP3 could not be rectified in time. The 107 percent time was 1m 46.217s, but at the stewards' discretion the red and white cars will be allowed to race.
The start of Q2 saw a mass exodus from the pits as everyone rushed out on mediums, this time desperate for banker laps as forecasts revealed rain would hit within minutes.
Rosberg set the pace with 1m 39.377s, but Hamilton was hampered by traffic - Mercedes couldn't get him out in time as his engine didn't fire up fast enough - and only just squeezed through. Vettel was second, only three-tenths off the Mercedes, with Williams' Valtteri Bottas next up ahead of Red Bull's Daniel Ricciardo, Lotus's Romain Grosjean, Felipe Massa in the second Williams, Toro Rosso's Max Verstappen and Hamilton. Daniil Kvyat in the second Red Bull and Sauber's Marcus Ericsson filled out the top 10.
Kimi Raikkonen was therefore the highest profile casualty of Q2, as the former world champion could only manage a 1m 42.173s that left him 11th and out of Q3. Pastor Maldonado also failed for Lotus, with 1m 42.198s, while the Force Indias were 13th and 14th on 1m 43.023s for Nico Hulkenberg and 1m 43.469s for Sergio Perez. It was also disastrous session for Carlos Sainz, who managed only 1m 43.701s for 15th in his Toro Rosso.
The heavens really opened after the first set of flyers, effectively sealing the order. From then, it became a matter of waiting to see just how bad the rain got. At 17.40 it was announced that Q3 would be delayed for at least 15 minutes, and the waiting began. With cars also going into parc ferme, decisions had to be made as to what settings to run as a hedge against the existing weather in qualifying and likely weather conditions on race day.
Eventually, Q3 got going, on a still-wet track, at 18.15, only half an hour late.
The smart teams put their cars on intermediates straight away, which meant that Williams, Lotus and Sauber erred in their choice of full wets and quickly had to switch rubber.
Vettel set the pace with 1m 53.178s before immediately being displaced by Rosberg on 1m 51.066s, but Hamilton got the job done beautifully with 1m 49.834s, at the time putting him more than a second clear of the field.
On their second runs Hamilton failed to improve, and as Rosberg came up short with 1m 50.299s it was Vettel who came dangerously close to snatching pole with 1m 49.908s for Ferrari.
Behind them, the Red Bull drivers were fourth and fifth, with Ricciardo on 1m 51.541s and Kvyat on 1m 51.951s, while a quite extraordinarily mature performance saw rookie Verstappen sixth on 1m 51.981s.
Williams’ mistake on tyre choice appeared to cost them, as Massa was only seventh on 1m 52.473s and Bottas ninth on 1m 53.179s. The pair were separated by Grosjean's 1m 52.981s. Ericsson's transformation continued, meanwhile, as he guided his Sauber to 10th.
Post-session, Grosjean was penalised two grid spots for leaving the pit lane out of sequence in Q2, thus the provisional grid reads: Hamilton, Vettel; Rosberg, Ricciardo; Kvyat, Verstappen; Massa, Bottas; Ericsson, Grosjean; Raikkonen, Maldonado; Hulkenberg, Perez, Sainz, Nasr; Button, Alonso.