Highlights - Chinese Grand Prix
By Martin Brundle
BBC F1 analyst
It was a great pleasure to witness the supreme skills of the all the drivers, but especially the McLaren duo as they claimed a great one-two for the team at the Chinese Grand Prix.
Jenson Button's victory was superb and, despite enthusiastically lauding his championship performance last year, I now realise I'm guilty of underestimating him.
He has now out-qualified Lewis Hamilton 3-1 in the four races so far, won twice and leads the world championship by 10 points. Mind you, he might not have won in Shanghai if I'd been a steward as you'll read later.
The conditions were challenging in the extreme and it was spitting with rain on the grid as the cars started on slick dry tyres. Button, Rosberg, and the two Renault drivers Kubica and Petrov benefitted most from having the confidence to stay out on dry tyres during the safety car period at the end of the first lap.
The intermediate tyres are softer this year and they are no longer the 'miracle tyre' which can bridge from very wet track conditions to a drying racing line.
When it rained properly and everybody took to the 'inters', the high-speed nature of many of the corners took a heavy toll on wear rate.
When the centre part of the contact patch wore virtually to slick it would have been so easy to snatch a brake, jump on the throttle too hard, lock the rear axle on downshifting - or run half a metre wide and sail off the track.
When the rubber wears thin the main issue is not water clearance but loss of surface temperature.
Button locked his brakes in the closing stages and ran wide at the Turn 14 hairpin; he never recovered the temperature and grip again and only just beat Hamilton over the line.
The way the two McLaren drivers approached the race under Shanghai's changeable skies was very different. Button made another canny tyre call and as a result he made two stops fewer than Hamilton.
What stands out for me is how calm and mature Button is these days. He's so comfortable in his own skin. I asked him in our 'red button' programme in Oz how he compared that victory with last year's. He was treading carefully but explained that last season he had the best car to win races and this year he doesn't necessarily have the best car and is still winning races. I believe that's why he's so satisfied and happy, he feels fully accomplished.
It was a fighting drive from Hamilton in Shanghai and he was truly spectacular as he came through the field. He has now made 32 competitive overtakes in just four races.
Because of the pit stops and the two safety cars - "I seemed to go three places forward and two back", he said afterwards - he simply had to attack, and he's currently easily the best in the business at that. But Button is outsmarting if not outpacing him for now.
Button, Hamilton and Nico Rosberg, who took third for Mercedes, were all worthy of their podium places and their consequent places in the championship.
Rosberg led the race for a long time and finished a competitive third after keeping his head at the end against Fernando Alonso's looming Ferrari.
He admitted he didn't think he could hold Alonso off and you can understand why Mercedes were cracking open the champagne for his second consecutive podium.
Schumacher frustrated after difficult race
Unfortunately, it was Michael Schumacher's worst weekend so far for the team. He was three-quarters of a second off the pace on the grid and, despite the safety cars closing up the field, he was 50 seconds behind Rosberg at the flag in conditions where he used to excel.
It's getting uncomfortable all round, and much depends on the Mercedes update for Barcelona now to recover Michael's confidence, pace and credibility. I still have the faith.
The curious second safety car - for debris on the track - made the race in many ways as it closed the pack back up. At that point, Hamilton was almost 50 seconds adrift of Button and Alonso another 20 seconds further down the road.
Alonso had a stroke of luck. He jumped the start wildly but his inevitable drive-through penalty didn't really hurt him as much as normal because of the safety cars and multiple tyre stops. He was aggressive when he needed to be but he couldn't make the overtakes stick like Hamilton.
Red Bull locked out the front row with Sebastian Vettel on pole ahead of Mark Webber but burnt their tyres out too quickly and their pit calls were a day late and a dollar short. They clearly have handling issues in those conditions.
I'm baffled by this as they have so much grip and downforce in the dry. Maybe the car is very stiffly sprung, but it doesn't appear to be especially so over the bumps and kerbs.
They just didn't have real pace even before their tyres lost interest and Hamilton caught and passed the pair of them as though they were standing still at one point.
The Renault looked driveable enough as both Kubica and Petrov did a very good job with the same engine, and this confirms that Red Bull's underlying wet track problems are with car set-up. I think they would have run away with a dry race frankly.
After the brutal and sometimes unfathomable penalties of the past few years we now seem to have swung the completely other way. I don't believe McLaren were guilty of an unsafe release when Hamilton nearly clouted the side of Vettel's car.
Hamilton and Vettel go side by side down the pit-lane
The lollipop man cannot watch everybody else's pit stop and second guess how much wheelspin his man will get on wet concrete.
But the subsequent driver behaviour down the pit lane was positively dangerous. Vettel shoved Hamilton towards the wheel guns and mechanics, albeit long after Hamilton should have yielded. They both received a reprimand, but what does that mean? How long does a reprimand last and how many are you allowed to collect before a real penalty?
They are lucky I wasn't the resident driver steward for the weekend because I would have strongly recommended dropping them both some penalty places on the grid for the next race in Barcelona. The decision taken has set a very dangerous precedent.
I'm more relaxed about side-by-side action into the pit lane entry, where no person or equipment is in the road. It has been interpreted before that this is against the rules.
On that subject, Alonso passed Massa with a cunning move into the pit lane. How did Ferrari recognise that so quickly and swap Massa's tyres, which were already in the pit-stop area, for Alonso's so they could be fitted first?
Finally, I would also have recommended at least a flaky reprimand if not a drive-through penalty when Button unreasonably slowed the pack for a safety car restart. It was a clear breach of the rules unless he could demonstrate that the safety car had been unreasonably slow entering the pit lane.
I wouldn't have been a popular steward with my former McLaren team but that job is not a popularity contest. Ask any referee.