The Australians are in town again for an ODI series, and Rohit Sharma, more than anyone else, will be licking his lips in anticipation. In general, his ODI form over the last few seasons has been exceptional - he has a 50-plus average in each calendar year since 2013, when he became a permanent fixture at the top of the order - but against Australia, he has elevated his batting to another level altogether: in 13 ODI innings against them since the start of 2013, he has scored five centuries and averaged 110.40 at a strike rate of 102.88. He missed a sixth hundred by a run when he was dismissed for 99 in Sydney in 2016.

After scoring a mere 193 runs in his first ten ODI innings against Australia, Rohit has gone into overdrive, scoring almost six times that tally in his next 13. It hasn't mattered much whether he has played them home or away either: in seven innings against them in Australia, he has scored 613 runs, including three hundreds; at home, he has 491 in six, with two hundreds, including a double. In the first ten of those 13 innings, his scores read thus: 42, 141 not out, 11, 9 not out, 79, 209, 138, 34, 171 not out, and 124 - 958 runs, at an average of nearly 137. That aggregate is the highest by any batsman against a single opposition in ten successive innings, going past Sachin Tendulkar's 778, also against Australia, between 1996 and 1998.

Despite his slow start against Australia, Rohit has notched up 1297 runs against them from just 23 innings, at an average of 68.26. Among batsmen who have scored at least 1000 ODI runs against an opposition, only two have higher averages: Hashim Amla versus West Indies, and Mohammad Yousuf versus Zimbabwe.

Clearly, Rohit's transformation as an ODI batsman began from the time he started opening the innings regularly, from 2013: till the end of 2012, he averaged 30.43 from 81 innings, at a strike rate of 77.93; since the start of 2013, he has averaged 56.10 from 76 innings, of which 75 have been at the top of the order, at a strike rate of 89.50.

Rohit Sharma's ODI career
Period Inngs Runs Ave SR 100s/50s
 Before 2013  81  1978  30.43  77.93  2/ 12
 Since Jan 2013  76  3759  56.10  89.50  11/ 20
 Career  157  5737  43.46  85.14  13/ 32

However, even within that period as opener, his batting has evolved over the last couple of years. In the early days at the top of the order, he still had the appetite for big scores and the ability to make his runs quickly, but the quick runs would only come after he had spent long periods at the crease.

In the 41 innings he played as an opener before the start of 2015, his strike rate in his first 20 balls was only 52.54, and in his next 20 balls it was 78.46. Before 2015, there were 11 instances of him facing 30-plus deliveries in a completed innings at a strike rate of below 70. His hundreds all came at faster than a run a ball, but there were also instances when he got out after consuming too many balls and not getting enough runs.

Since the start of 2015, though, his scoring tempo has been much better early in the innings, even if he hasn't quite exploded with his big hitting later in the innings. In the first 20 balls, his strike rate has increased to 74.89, which is a 42% improvement over his rate before 2015. Similarly, in the next 20 balls the strike rate has improved by nearly 25%, from 78.46 to 97.67, and from 71.09 to 90.55 in the 41-60 balls period. This increase in tempo right through the innings has also ensured that his partners haven't been put under undue pressure to make up for Rohit's poor scoring rate in the early part of the innings.

In fact, in 37 innings since the beginning of 2015, there hasn't been a single instance of him facing 30-plus deliveries in a completed innings at a strike rate of less than 70, whereas there were 11 such before 2015. His slowest innings of this sort in this period came in the World Cup semi-final against Australia in Sydney, when he made 34 off 48 (SR 70.83).

With experience, Rohit has clearly improved upon his ability to find the gaps and pick up boundaries early in his innings: his balls-per-boundary figure in the first 20 balls has improved from 14.3 to 9.6 in these two periods, while it has improved from 12.2 to 9.0 in the next 20 balls.

The move up the order to open the batting has worked like a charm for Rohit. Since the start of 2013, he averages 56.10 in ODIs, which is fourth highest among all batsmen who have scored 2000-plus runs during this period. Since the beginning of 2015, his average has been even higher - 60.15, which is again fourth with a 1000-run cut-off; only Virat Kohli, AB de Villiers and David Warner have done better.

Rohit has racked up hundreds for fun since turning opener, getting 11 in 78 innings. His rate of 7.1 innings per century is next only to those of Amla and Quinton de Kock among openers with five or more centuries. Rohit is 30 years old now, an age when batsmen generally peak; the next few years could well be the best ones for him in the 50-over format. To start with, there is the small matter of taking on his favourite opposition team.

Least innings per 100 for openers in ODIs (Min 5 hundreds)
Batsman Inns 100s Inns_per_100
  Hashim Amla  150  25  6
  Quinton de Kock  82  12  6.8
  Rohit Sharma  78  11  7.1
  David Warner  93  13  7.2
  Sachin Tendulkar  340  45  7.6

With inputs from Shiva Jayaraman

S Rajesh is stats editor of ESPNcricinfo. @rajeshstats