Around 2.30pm on July 2, 2009, Rangana Herath was preparing to go to the gym on a day off from training with his Staffordshire club. Had he left without his phone half an hour earlier, he might still be kicking around the first-class circuit. Sri Lanka might still be awaiting their first Test win since Muttiah Muralitharan's retirement. Their biggest away win in 13 years might never have transpired.

He remembers the day clearly, and the call he feels changed his life. Murali had damaged a tendon while training ahead of Kumar Sangakkara's first Test at the helm, and he had suggested to the new captain that Sri Lanka fly Herath in as cover. They were both on the line when Herath picked up. Sangakkara made the proposal.

"Ranga, there's a Test match in Galle, not tomorrow, but the next day… Can you make it?" Thirteen thousand kilometres away, there was only ever going to be one answer.

"I didn't even think about the fact that not only was I in England, I was in Stoke-on-Trent, which was about four or five hours from the London airport," Herath says. "I hung up the phone and thought, 'I've given my word, so I've got to go now.' On the way, I thought to myself, this will probably be my last opportunity. I was 31 at the time, and at that stage, happy to still be considered. I knew I needed to give it everything."

Less than a week later, Pakistan began the fourth morning in Galle needing 97 for victory and with eight wickets in hand, after Sri Lanka's underwhelming batsmen had set them 168. Salman Butt had batted securely in the second innings, beginning the day on 28 not out, while Mohammad Yousuf, a first-innings centurion, was unbeaten on 12. Sangakkara took a gamble on Herath to open the bowling and, in four balls, he dismissed the overnight pair and set Pakistan's fatal slide in motion. By the end of his second spell, Herath had dismissed four batsmen and conceded nine runs in 10.3 overs. Pakistan lost the match by 50 runs and the three-match series, 2-0. Herath finished second-highest wicket-taker and has been a fixture in the side since.

"That was a turning point for me," he says. "I sometimes think that if I had declined the offer to come, because it was going to be too tough to get to Galle, I might still be in England or someplace else."

Where he is, instead, is at third place in the ICC's Test bowling rankings. He is not often considered for the title of Test cricket's premier slow bowler, but he outranks every other spinner, and since his recall, has taken his wickets at a marginally better average than both Graeme Swann and Saeed Ajmal. Herath has had helpful tracks to bowl on at home, of course, but in that period, he has also outperformed Swann and Ajmal in Australia and South Africa by both average and strike rate.

There can be little doubt too that Sri Lanka's Test fortunes pivot on Herath, to nearly the extent they did on Murali. In Sri Lanka's five Test wins since Murali gave up the whites, Herath has taken seven five-wicket hauls, reaping 49 of the 100 opposition wickets - a larger share of the victory spoils than even Murali claimed in a staggering career, notable for its profound impact on the team's fortunes.

Yet, though he is the nation's best current cricketer, he remains unmistakeably an everyman, stardom having forgotten him, or he it. There is no IPL contract padding his wallet, no major sponsors have plastered his rotund figure on the island's billboards and, until March, he was not even in Sri Lanka Cricket's top contracts bracket. Herath still has a day job at a Colombo bank - though it is now not much more than a series of long duty leaves. He asks for another six weeks off from the human resources department in the same bashful tone that he addresses groundstaff at the Premadasa Stadium, from whom he needs the key to a locked door.

"Being a cricketer in Sri Lanka is no hassle at all," he says. "It's just my wife, our baby and myself at home, so I'm the one who goes to the markets and runs all the errands while she stays back. I've never had any issues."

"When I'm bowling, I don't stop thinking. Batsmen aren't afraid to step out and hit you. If you are thinking about every one of your six balls every over, you give yourself the best chance to succeed"

He chuckles at himself as he recalls the stunning catches he has taken in the recent past, three of which are as memorable as any to have been nabbed by his more athletic team-mates.

"Those catches come once in a while for me. I guess when I do my job well as a bowler, that confidence seeps into the other areas of my game as well. I try to be safe in the field, but those kinds of catches you can't really plan."

The most recent of the three takes - a stellar one-handed grab above his head, while back-pedalling towards the boundary - came during the 2012 Boxing Day Test, when he waged a lone war on Australia as his team-mates continued to shell chances off his bowling and flounder hopelessly with the bat. Exactly one year before that, they had held their catches, and given him sound totals to bowl at, as Herath led the side to a remarkable comeback victory in Durban, their first ever on South African soil, and the last time the now top-ranked side were defeated. In the last two years, Herath has not only become the side's primary match-winner but also their most consistent performer, win or lose. Like Murali, he is at once spearhead and workhorse, only, bereft of outrageous talent, he is not quite as talismanic.

"I think at some point I realised how important I was to the team, and that's when I really lifted my game. That responsibility was a blessing, because it helped me go to the next level. When I bowled poorly, I felt like I had really let everyone down. But at the same time, now, I don't think about the pressure on me to take wickets. I think that would be a mistake, to pile something unnecessary on top. I keep doing the thing I know how to do."

Subtlety is what Herath does best, working off an uncomplicated action, which in turn affords him uncanny accuracy. In an era when subcontinent spinners worship variation, Herath is foremost a disciple of flight, in all its myriad forms. Tossed up, ripping deliveries are punctuated by meticulously calculated darts, straight ones, and over-spinners. The trend may be to pursue unplayable, deliveries that depose batsmen in a single swipe, but instead Herath builds a steady narrative with each spell. Some balls are delivered in front of the umpire, others from wide out, more still with a round-arm action, each adding a new thread to the plot. Often, it is only when his prey is strung up on Herath's web that the entire machination comes into view. You wonder how you hadn't seen it all along.

"When you start reading the batsman and watching what he's doing with his hands, his feet, and you start reacting to that and figuring out how you can put him in trouble with the strengths you have at your disposal - that's when you take your bowling up a notch. When I'm bowling, I don't stop thinking. You have to do that in modern cricket. Batsmen are always trying new things themselves, and they aren't afraid to step out and hit you. If you are thinking about every one of your six balls every over, you give yourself the best chance to succeed."

He is quick to point out though, that his bowling is not devoid of variation. Among modern spinners, he is the pioneer of the carrom ball: the flicked delivery that turns the other way. But his version, he admits, is no longer the best in the market. Ajantha Mendis' and R Ashwin's imitations are better disguised and Sunil Narine's achieves more turn. Herath uses his "other one" sparingly, and as his hauls have become heavier, batsmen have grown wise, and dulled its effect.

In March, Herath celebrated his 35th birthday with a 12-wicket haul against Bangladesh, becoming only the third Sri Lankan bowler to take 200 wickets. The year should have had much more in store for him in his favourite format, but five Tests were removed from the calendar, leaving only a Zimbabwe series to look forward to before a year-end tour to the UAE in December.

"I don't have any targets in terms of numbers that I want to hit. I'll have to take it series by series, and think about the needs of the team and my own fitness and performance. There are a few young spinners now, who are coming through and they need to get that opportunity as well."

As Sri Lanka's new rock, and lately their sledgehammer, Herath has propped up a side in transition, and eased the loss of their greatest ever cricketer. Neither his hunger nor his art shows any signs of subsiding, but in three years, Herath has already left an indelible mark on his nation's cricket history.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. He tweets here