If you have agonised over India coming close and not winning on the tours of South Africa and England this year, you probably watched the Adelaide Oval Test from behind your sofa once India got into Australia's lower order. All those memories of stubborn lower-order runs would have come storming back with every over a lower-order wicket didn't fall.

How has Virat Kohli fared this year at the toss? ESPNcricinfo Ltd

A lot has been written, said and tweeted about India's ability to dislodge tails. From Cape Town to Birmingham, from Centurion to Southampton, India's conservative approach against the lower order has been identified by many, including the team management themselves, as the failure to "seize big moments". Virat Kohli has marvelled at the opposition allrounders' clear minds and fearless batting.

Yet, a lot of this fear might have disregarded something significant but so obvious that it can be lost. All the lower-order resistance against India came with the opposition ahead in the game, not necessarily on balance but on runs, any runs. When Sam Curran began his onslaught at Edgbaston, England were effectively only 100 for 6, but they were not in deficit, and they were going to make India chase something, anything. South Africa's lower order rallied in Cape Town and Centurion when they were ahead on runs. In Southampton, England might have given up a first-innings lead, but the complexion of the game changed as soon as they drew level again even though they had lost a wicket by then.

Home advantage is arguably bigger than it has ever been in Test cricket, but the advantage from winning the toss and batting first hardly gets analysed that much. Perhaps because the athletes are too proud to talk about luck. However, in Test cricket today, there seems no way back for a side batting second and falling behind or drawing level or even taking an insignificant lead. Not counting beating Zimbabwe, Bangladesh and West Indies, the last time a side batting second won a Test despite falling behind was back in 2015 when New Zealand overturned a 55-run deficit against Sri Lanka in Hamilton. The last time an away side managed this feat - again not in Zimbabwe, Bangladesh or the West Indies - was back in 2008, when South Africa chased down 414 at the WACA Ground.

As a comparison, sides batting first are far likelier to overturn a first-innings deficit. New Zealand did it twice in the recently concluded series against Pakistan. England did it against Sri Lanka in Kandy and against India in Southampton. India themselves came back from a deficit in Johannesburg, just as they did against Australia in Bengaluru. The cliché that Test cricket gives you a second chance applies almost exclusively to sides batting first these days; at least in Tests between fairly evenly matches sides at any rate.

There has been a clear and consistent dip in the win-loss ratio of sides fielding first in Test cricket. Most of the years, with the odd exception, the ratio hovered between 0.8 and 1.2, but starting 2014, it has been 0.5, 0.48, 0.48, 0.54, and 0.31 in 2018. Hence you really have to question England's decision to insert India in at Nottingham earlier this year. Hence you also need to be a little sympathetic towards India's away record in 2018. This is only the second toss they have won in nine. They won the first match (in Johannesburg), and are in a situation where they should back themselves to win the second.

This begs the question if toss advantage - rather bat-first advantage - is more significant than home advantage. Over the same last five years, the win-loss ratio for away sides has been 0.5, 0.6, 0.61, 0.46, and 0.48 in 2018. There isn't much between the two then. There is reason to believe they might be both just as significant. If you look through that prism, India faced the double whammy of home and toss advantage in seven of their nine away Tests this year. In one of those, England were merciful enough to ask India to bat, an opportunity India cashed in on. The Lord's insertion was done in freakish conditions, one of the rarest of rare scenarios in which you opt to bowl first in modern Test cricket.

If India go ahead and achieve the win they are favourites for in Adelaide, they will have shown they have been good enough to cash in on every opportunity presented to them. At home, they won 4-0 despite fielding first four times out of five against England in 2016. Prior to that, in 2013, they blanked Australia 4-0 despite fielding first in all matches. That they can nullify the toss advantage at home, and encash almost every time they have the advantage away is precisely why the tag of the best Test side in the world is well earned.

Let's try to look at what this bat-first advantage translated into on the field in Adelaide. The criticism of India in letting lower-order partnerships flourish has been the spread-out fields for the set batsman. In this innings, India only sent out one extra boundary rider than they normally would for Travis Head. They were much more willing to take a risk here. In the absence of the fear of batting last, India were much more enterprising.

Virat Kohli and Tim Paine pose with the Border-Gavaskar Trophy ahead of the first Test Getty Images

During the said matches that India conceded too many runs to the lower order, it isn't as if India's lower order didn't score runs. Kohli and the tail did that in Birmingham, Cheteshwar Pujara did so in Southampton to even get them the first-innings lead; Kohli had sizeable partnerships with R Ashwin and Ishant Sharma in Centurion, but they were batting last in those matches. That was the difference.

This won't be a pleasant notion for many Test cricket romantics, for a Test win is built on so many small things going right. To suggest that something based on dumb luck probably has a bigger bearing on the result than all those small factors put together can't be that palatable. But that's where Test cricket today is, especially when two evenly matched sides are involved.

These were two really unlucky sides coming into Adelaide. India had lost seven out of their last eight away tosses. Australia had lost 11 of their last 14 tosses. Somebody had to get lucky. It was just as well that India did because home and toss advantage has been a lethal combination. In this Test at least, toss advantage seems to be trumping home advantage even after a below-par first innings. You'd dearly love to be proven wrong, but chances are high that this series between these evenly matched sides might just be decided by who is batting first more often.