Twenty20 cricket will probably evolve to a form one day where many sides will look like Mumbai Indians. A side whose batsmen will never let the bowlers get on top. Many sides will one day have enough efficient power hitters to just keep going. In the here and now, though, we have sides in the IPL reaching the playoffs with no back-up for their two or three big hopes. Once the game gets down to them, it is either AB de Villiers or bust. Or Kane Williamson or bust. That is why they can't play with the freedom of a Suryakumar Yadav or an Ishan Kishan.

Add to it memories of two blown chases. Against these same opponents, in their first match of this IPL, Williamson's side sat pretty at 121 for 2 chasing 164. They lost by 10 runs. On another night, chasing just 127, they lost by 12 runs to Kings XI Punjab.

Add to it the pressure of a knockout. Not just any knockout, but a knockout that you have entered on the back of three wins in three must-win matches against the three top sides in the tournament. Add to it an injury to one of your few good batsmen. Add to it a dodgy DRS call to send back the other.

Most importantly, add to it a slow pitch with appreciable turn and four international spinners in the opposition. The choke is well and truly on. Williamson is part of that choke, crawling and spluttering. When he was joined by Jason Holder, the last 49 balls had brought just 24 runs and three wickets.

There are two ways of dealing with such a situation: counterattack and break the back of the chase, which is 65 off 49 now or absorb the pressure and be calculating. If you are Mumbai, you probably take the first option, knowing there is Kieron Pollard and Hardik Pandya behind you to do the job. You probably don't even let it get to this stage. If you are Williamson and the Sunrisers, though, you know you are not winning this before the 19th or the 20th over.

Williamson's biggest enemy was the conditions and the big boundaries. Any attempt to hit a boundary had to be precise and to a ball was that either too short or too full. Anything else was not an option. And while the format takes its time to evolve, Williamson is the best man conceivable for these calculations.

Before he got to the fast bowlers, Williamson only just tried to hit two boundaries. The spinners were not giving him anything short so he had to wait for something too full so he could attack it before it could misbehave. It is easy to say perhaps live time that pressure got too much and Williamson took two calculated risks, but go back and look at the pitch maps. When he first slog-swept Washington Sundar for a six with the requirement 59 off 38, it was the only full ball of the over. So all that while when pushing singles down the ground, Williamson had been on the prowl, waiting to launch into an error in length. And this ball was not that full either, just fuller than the usual Sundar cluster that you see. One half error, and he jumped onto it.

With Yuzvendra Chahal, whom Williamson slog-swept for the second six, it was a matter of line. This was the last ball of Chahal's spell - his figures 3.5-0-18-1 till then and with 41 still required off 25 - and this is the most leg-side he ever got to Williamson. Everything else had been off, off and middle, but this one allowed him to open the front leg up. Just the two attempted big shots, both nailed, and Sunrisers needed just nine an over with pace on the ball in the last four overs.

Even then Williamson didn't take any extravagant risks. He drove Shivam Dube along the ground, and then looked to repeat the delicate late-cut he played off another slow medium bowler, Andile Phehlukwayo, in the World Cup match at Edgbaston. In a way these are similar chases. The pitch was slow, the bowlers were making it tough, and you couldn't trust a new batsman to get going immediately. He finally managed that dab and that boundary off the pacier Navdeep Saini.

Given the resources, this was a perfectly paced chase for a side used to messing these chases up. If the future will have place for Williamson or not, if Williamson will adapt enough to fit himself in the future or not, here and now is the time to revel in the efficiency and the calm of Williamson, without whom Sunrisers probably would have been out of the tournament.

Sidharth Monga is an assistant editor at ESPNcricinfo