Ryan Harris, all bustling pace and wickedly late movement, has become Australian cricket's most precious bowling commodity. The great pity for Harris and Australia is that at the age of 31 he is also among its most fragile. The heavy rain that shrouded Pallekele and ruined any chance of a result on the final day could not obscure the outstanding quality of Harris' bowling on a dead pitch. But a hamstring scare illustrated why Australia's team management had already discussed the possibility of resting Harris for the final Test in Colombo should the series be decided.

Those who first saw Harris bowling at little more than medium pace for South Australia, with the Redbacks keeper Graham Manou standing up to the stumps for him, have been endlessly amazed and fascinated by the leap he made in subsequent years. He gained in pace, accuracy and self-assurance, augmenting the amiable temperament that made him a popular team man even before first-class and Test wickets started to arrive in bunches.

Harris himself puts the change down to growing up, gaining in fitness and strength, and also becoming a little more comfortable in revered cricket company after years of uncertainty and single-season contracts with South Australia. Adelaide's rusted-on cricket culture, which alternates between extremes of lethargy, drinking and infighting, might also have held him back. Nonetheless, he was as quick, if not as confident, as he is today before he chose to leave. A move to Queensland - they offered a three-year contract following Harris' one and only full season with SA - completed the transformation.

Australia's success thus far in Sri Lanka could not have taken place without Harris' combination of speed, swing and seam, all achieved with a level of accuracy that has given the hosts very little room to manoeuvre. His run to the wicket and bowling action are things of more power than beauty, making his epithet "Rhino" all the more fitting. But he explodes through the crease with exceptional rhythm at his best, then utilises a strong wrist and seam position to gain the sort of deviation few batsmen can counter. In Pallekele, Harris defeated top-order opponents in each innings by conjuring the most dastardly of tricks, shaping the ball one way and then seaming it back the other.

On the first morning it was Tharanga Paranvitana who could not counter this, edging behind to Brad Haddin. But the collector's item was the wicket of Kumar Sangakkara, seemingly entrenched for a long stay to make the game safe on day five. Harris' first over with the second new ball had been met largely with the full face of Sangakkara's bat - he was seeing it well enough. Then in his second a straighter deliver curled subtly in the direction of leg stump before zipping towards the off. Sangakkara's bat was angled, understandably, towards wide mid-on, and the cut away from him resulted in an edge to Michael Clarke at second slip. Clarke's praise for Harris after the Galle Test was the warmest a captain could offer to his bowler, and on the evidence of this ball it was entirely warranted.

Among other international bowlers in 2011, perhaps only South Africa's Dale Steyn and the English quartet of Jimmy Anderson, Stuart Broad, Chris Tremlett and Tim Bresnan can be considered Harris' equals or betters with the new ball in hand. Across the admittedly small sample of seven Test matches, an average of 20.90 and strike rate of 42.6 places Harris in the most rarified of company. Steyn's 238 wickets at 23.21 and a strike rate of 39.9 has him well out in front as the most destructive bowler of his time, but the comparison with Harris will be intriguing if the Australian can hold his body together for the Test matches in South Africa in November.

This, unfortunately, is a more open question than anyone would like it to be. Harris' career has been so speckled with injury troubles that the Australian team hierarchy is presently grateful to have him for however long he has, even if it is only a handful more matches. Following last year's Perth Ashes Test, in which Harris' nine wickets played a key part in securing Australia's only win of a dire summer, he spoke candidly about the battered knee that requires constant management and selective training to keep him on the park. He is closer than most are to their surgeon.

There was plenty of painful irony then at the MCG, when it was not Harris' knee but his ankle that fractured under the stress of his whole-hearted run to the bowling crease. The break ended his season, and he was not sighted again until the Indian Premier League, which he used as a warm-up to the upcoming Australian schedule with a program more dedicated to physio and rehab than the bars and parties that would have been his usual haunts in earlier years.

During that latest convalescence, the Australian selectors decided that in future they would use Harris as a Test match specialist, leaving him out of the ODI squad for Sri Lanka even though his record in the format - 41 wickets at 16.12 - is even more spectacular than his Test match figures. To that end Harris trained with longer spells and back-to-back Tests in mind, and in Pallekele he pushed himself through a number of punishing stints at the crease, extracting life from a pitch that had very little to offer once the initial moisture of the first morning had evaporated.

After Sangakkara he took one more wicket for the Test, his sixth, when Prasanna Jayawardene edged a ball that left him after the previous two had angled in towards his stumps. The celebrations were soon followed by the worrying sight of Harris heading off to assess a hamstring complaint, and there were plenty of concerned looks among his team-mates as he left. They know exactly how much Harris can add to the Australian attack when he plays, and how much is lost when he does not.

Daniel Brettig is an assistant editor at ESPNcricinfo