Last Saturday afternoon, the day before the South Africa match, India coach Anil Kumble placed three cones in the short-of-a-length area on one of the practice pitches at the Oval. Then India's fast-bowling group, comprising Bhuvneshwar Kumar, Jasprit Bumrah, Mohammed Shami, Hardik Pandya and Umesh Yadav, ran up and hit the placed targets repeatedly as Kumble kept close watch from behind the stumps.
To the untrained eye, it seemed like the seamers were focusing on finding the right length - and it might have been that - but the primary objective, it turned out, was different.
Kumble would have studied the inconsistent lines India had maintained against Pakistan and then Sri Lanka and hence wanted to make corrections. He knew the straight boundaries, and the one at square leg towards the Peter May stand, were on the shorter side. The smallest error in line could lead to a lot of runs and, ahead of a must-win match, India had to plug every possible weak link.
Next morning, Bhuvneshwar and Bumrah put into practice what they had learnt, tying up the South African opening pair of Hashim Amla and Quinton de Kock with tight lines and unbeatable lengths. The slowness of the pitch - it was being used for the second time in three days - added to the batsmen's misery. The slow pitch did not help the bowlers either, forcing Bhuvneshwar and Bumrah to bowl defensive lines.
South Africa did not utilise the field restrictions in the first 10 overs and seemed happy to be 35 for 0. But when they started trying to up the run-rate, Amla and de Kock perished. The onus was now on the middle order to patch the innings up but all that followed were two embarrassing run-outs. South Africa had succumbed to the pressure built by the Indian bowlers and their agile fielders. AB de Villiers, after the defeat, admitted his batsmen had been "squeezed" dry.
To an extent, England's hard, dry pitches have surprised the Indian fast bowlers, who were expecting conditions where they could find movement in the air. The absence of swing made the jobs of newcomers like Bumrah and Pandya that much harder.
Most bowling teams try to attack when the ball is new, and that is what India had done as well in their first two games of the Champions Trophy. But, in light of the unhelpful surfaces, plans had to be changed. Having given away 51 and 44 runs in the first 10 overs against Pakistan and Sri Lanka, India improved significantly against South Africa.
"Generally, we always go for wickets in the first 10 overs when the ball swings," Bhuvneshwar said after the side sealed the semi-final spot. "But now we look to contain them and then take wickets when pressure builds. Teams try to save wickets till the last 10 overs before going big at death. That is why we thought our plan should be to contain in the middle segment to limit the total to not more than 300."
Having played in the 2013 Champions Trophy also held in England, and in India's Test tour of the country the next year, Bhuvneshwar knows these conditions well and has been heavily involved in making the team's bowling plans. "The only thing you have to change is length. Everyone is bowling a bit back, compared to what they normally bowl."
India's lengths in 2017 have been virtually similar to those they bowled in 2013, when they won the title. Of the 20 wickets the fast bowlers took then, 13 came from deliveries that were short-of-a-length. By accessing that same area of the pitch in this edition, the quicks have produced five of their 12 wickets.
Understanding such nuances will certainly help the growth of up-and-coming players like Bumrah. He was given the new ball for the first time in the tournament on Sunday and did well enough (2 for 28) to earn the Man-of-the-Match award. "The wickets have been a little different," he said. "I expected slightly different wickets - the wickets are a little hard, favouring the batsmen.
"You have to be proactive, you have to vary your lengths all the time and you have to be consistent as well. So the margin of error is quite less. We were just focusing on that and trying to hit good, hard lengths and not to give them room."
As for Kumble's exercise before the South Africa match, Bumrah said, "Basically he was telling about the lines. You don't want to give room to the batsmen because there is no lateral movement. There is no swing or seam on the wicket.
"They are very flat so you can't be one-dimensional. If you continuously bowl on one area, the batsman would line you up. With the four-fielder rule [outside the circle between overs 10 and 40] it is difficult for the bowlers as well, so you had to use the occasional yorker or a bouncer and it worked."
Virat Kohli has become better at making moves in the middle as well. He brought R Ashwin to bowl as early as the 10th over sensing South Africa were itching to accelerate and the moment they tried, it resulted in a wicket.
But it was India's fast bowlers who made the biggest difference on Sunday. Regardless of the conditions - and despite being surprised by them - they have worked hard to follow the lines Kumble has drawn.
Nagraj Gollapudi is a senior assistant editor at ESPNcricinfo