Sebastian Vettel's dominant victory for Red Bull in the Korean Grand Prix really puts him in the driving seat to win his third consecutive drivers' title this year.
It was Vettel's third win in a row and there are lots of little reasons that add up to make what has clearly been a big step forward in performance in the Red Bull car.
Red Bull did not start the season that strongly but they have learned a lot about the car as they worked through its problems and the effect of that is being seen now.
The front wing they introduced in Singapore two races ago was a decent step forward for the whole car. It fully focuses on improving the overall airflow - particularly to the underfloor, where the most efficient downforce is created.
Then there is the new 'double DRS' system, which takes the overtaking aid fitted to all the cars a step further by operating on the lower rear beam wing as well as the rear-wing main plane.
It means they are able to run more downforce but still maintain a fairly decent straight-line speed with the DRS open in qualifying. It also helps get the tyres working better in qualifying, although it only works for them in the race if they qualify at the front.
That's because you haven't got the straight-line speed you would need in a racing situation, but you have the extra downforce to help look after the tyres and give a bit of extra lap time to get away at the beginning of the race, as we saw happen in Korea.
Red Bull also changed the rear suspension geometry a few races ago to reduce the degradation of the rear tyres.
They have put more camber-change on it. That means they can run the car with less static camber, so the tyre has a bigger contact patch for better traction out of slow corners but the high-speed performance is not affected because the necessary camber change is induced by the suspension movement.
In Korea, they also had a new sidepod arrangement at the rear of the car.
Normally, there is quite a big duct parallel to the floor which feeds the air into the diffuser to help re-attach the airflow through the central part of the diffuser.
They have changed that a bit, reducing the size of the duct, which means they have a better 'coke-bottle' shape to the bodywork at the back of the car, improving the airflow inside the rear tyres.
The new DRS system is influential in this because the way it interacts with the rear aerodynamics means they don't have to feed as much airflow through the floor.
It is a lot of small changes, but if you're looking for one big one, it's the front wing, which has made the airflow over the whole car work differently.
Add all that up, put Vettel in the fastest car, and he is going to be difficult to stop.
FERRARI AGONISINGLY OUT OF REACH
The Ferrari is not that far behind the Red Bull and, if they can find a couple of tenths of a second, it might make a big difference to Fernando Alonso's title hopes.
It's difficult to assess the race lap times from Korea because the race was so dominated by the drivers having to look after their tyres. The race strung itself out a bit and then just stayed there.
The Ferraris set the second and third fastest laps of the race, with Felipe Massa faster than Alonso.
I produce spreadsheets that analyse the lap times over the whole season and Alonso is something like 0.6secs faster than Massa on ultimate performance this season. So if Alonso was trying to chase down the two Red Bulls, perhaps he could have chanced the tyres a bit more.
There is talk of a big Ferrari upgrade coming soon, which is good because, other than wing optimisation for the different circuit layouts, the car has stayed basically the same for a fairly long time. And the races are running out.
In a straight fight between Vettel and Alonso, the Red Bull is too strong and Vettel would come out on top. In Korea there was no-one interfering in the Red Bull-Ferrari fight, but McLaren could well do in the remaining four races, so Ferrari need to do something about it and fast.
McLaren had a terrible time in Korea. Jenson Button's weekend unravelled when he qualified back in 11th. With that car, in a top team, with two world-class drivers, that should not happen.
Problems of one kind or another have cost McLaren a lot this season, whether it be slow pit stops early on or the reliability problems that have hit both Button and Lewis Hamilton in the last four races.
McLaren dominated four races in a row not so long ago and, even if Red Bull have closed them down and overtaken them, they still have a very quick car.
Until the last three races, no-one has dominated. For most of the season it has been about consistency and making the podium every weekend, and errors have cost McLaren dearly.
Team boss Martin Whitmarsh admitted it was the worst race he could remember by the team and I'm sure McLaren will go back to base and scratch their heads about what is going wrong.
Another team that need to do that are Mercedes. It was a very poor weekend for them. Qualifying ninth and 10th, behind a small team like Force India, is not good enough for a team the size of Mercedes - and they went backwards in the race as well.
Nico Rosberg was wiped out on the first lap, but Michael Schumacher's race was anonymous and he slipped back to finish 13th.
I've been speaking to a few of the guys there and they say there are so many people that nobody makes any decisions any more.
It's only three years since the same team - then called Brawn - won the championship.
OK, they had lots of Honda money to develop the car and the secret weapon of the 'double diffuser', and it wouldn't have happened without that. But back then it was a one-man band with Ross Brawn leading the team - and then, when Honda pulled out and they cut the workforce back, it was even more like that.
Now, after a major recruitment programme, they have a multi-man band and there are four guys in there who have been technical directors at other teams all doing different roles.
Meanwhile, Red Bull have Adrian Newey. He has a great team of people around him but he is the captain of the ship.
Brawn argues that everyone at Mercedes has defined roles and knows what they're supposed to be doing and the parameters of their responsibility.
But you have to look at their slide in performance after a promising start to this season and say something is going badly wrong there.