At around 12.50pm on a hot Saturday afternoon in Mumbai, December 10, Alastair Cook called for an ambitious lbw review. At the same time, in Bangalore, Prema Nair, a teacher at Chinmaya Vidyalaya in Koramangala finished her walk back home. The replays were on when she entered. This was an offbreak from Moeen Ali, which her son, Karun Nair, playing his second Test, had looked to defend. The umpire saw the bat and pad close together, and also figured the ball was turning too much so ruled it not out. The odds for this getting overturned were long. Yet everything went right with the review: from round the wicket, the ball turned enough to miss the inside edge but not the leg stump.

Here we go again, Prema thought. She doesn't watch Karun bat. She locks herself up in a room and worships when he bats. She watches the IPL games but not Delhi Daredevils' batting. She can't bear to watch. She gets too nervous. So her husband Kaladharan tapes the games, and she watches them later. This Saturday review against Karun just reinforced the superstition for her.

Kaladharan, 62, found it difficult to convince his wife, 59, to come to Chennai to watch her first cricket match, and had to play on her emotions to win her over. "How will I go alone?" "How will you stay back alone?" "This is his first Test in south India." So finally Prema relented. Having seen - through moist eyes - her son bring up his first Test century, and then go on to make it only the third triple by an India batsman, Prema finally believes that she can't bring bad luck to her son. A son for whose career both parents - middle class with no back-up if cricket doesn't come off - have made a lot of sacrifices. How could she ever possibly bring him bad luck?

The thing, though, is that luck has been a big thing in the Nair family. It has also been cruel. In July, having made his India debut in the limited-overs series in Zimbabwe, Nair went to Alleppey in Kerala to make offerings as gratitude for getting his India cap. The current in the river was too strong, and the snake boat capsized. Everybody swam for safety as you do in such situations. Karun made it, but only later did he realise that the relatives who had organised the trip couldn't.

A religious trip for good luck had turned into something horrible. It was bound to affect Karun deeply, but his family and relatives tried to keep him distracted, and get him back to cricket. No matter what you do, though, if you are the superstitious kind, the following incidents can bog you down. On the A tour of Australia in August and September, he managed just 38 runs in four innings. On Test debut - which was a last-minute decision thanks to an injury to his good friend KL Rahul - he was run out by his captain Virat Kohli after some freakish fielding. In his second Test, he dropped England's debutant Keaton Jennings before he had scored - Jennings went on to make a century - then fell victim to that improbable review on 13.

Karun Nair's parents watch him during his triple-century at Chennai ESPNcricinfo Ltd

It is difficult to break into the India batting line-up. In three years, they have handed out one cap to a batsman - Rahul. Karun was a week shy of his 25th birthday when he finally got the call. His batting is not as explosive as Rahul's. He is not a flamboyant person. He and Rahul are both friends, they have played almost all of their cricket together since the age of 11, but Karun is more subdued. "I think he once felt like getting tattoos [like Rahul], but I said it's not a good thing and he has stayed away," says Kaladharan. There are bound to be fears you are not cut out for international cricket, when the fates seem to be conspiring against you.

All those fears have been quashed now as the Nair family and friends watch Karun race away to a double and then a triple-hundred in a match that he got because Ajinkya Rahane got injured in the final nets session in Mumbai. At one point, Karun looks to play a vertical sweep as left-arm spinner Liam Dawson fires a defensive delivery down the leg side. "No, not that shot," says his father, "there is a short fine leg in place." A friend next to him says, "No, no, it's okay, he is hitting down on it, into the ground."

"Like Sachin Tendulkar used to," says Kaladharan. "He likes that and the reverse sweep."

Kaladharan should know. He goes to every match Karun plays in Bangalore. A mechanical engineer who was posted in Jodhpur when Karun was born, Kaladharan moved to Bangalore and has also worked on the sprinkler system on the Chinnaswamy Stadium outfield. Karun knows his father is there in the stadium when he plays Ranji Trophy matches at Chinnaswamy but doesn't point to him when he reaches milestones. In Chennai he does. At every milestone, after acknowledging his team-mates, he turns towards the Pattabhiraman Gate End and points to Level 1 of F Stand.

The proud parents are sitting there, living every moment of the innings, trying to come to terms with what has just happened. Their shy son, who doesn't speak much, who watched old videos of Sunil Gavaskar and Kapil Dev when little, whose main pastime was PlayStation. Their prematurely delivered son, with weak lungs as a kid, who would keep falling down and crying as a baby. Their triple-centurion son.