When South Africa tour England later this year for a three-Test series, the No. 1 position in Test cricket will be on the line, no matter what the results of the matches leading up to that series are. Even if England beat Sri Lanka in the ongoing Test at the P Sara Oval, and then swamp West Indies 3-0, they still wouldn't have put enough distance between them and South Africa to make the result of the series between the two redundant.

Among the several head-to-head battles to look out for in that series, perhaps the one that stands out most is the one between the lead strike bowlers of each team. Dale Steyn has generally been recognised as the best fast bowler going around for a while now, and his stats fully support that argument: since the beginning of 2007, Steyn has taken 240 wickets in 45 Tests at 21.48, which is way better than what any other bowler has achieved. During this period he has a strike rate of 39.3 balls per wicket, with 15 five-fors and four ten-fors.

In terms of wickets, the bowler in second place during this period is James Anderson, who, if everything goes well between now and July 2012, will be England's main man with the ball in that series. Anderson has taken 214 wickets at 28.46 during this period, numbers that leave no one in doubt as to who's been the best during this period.

It's only in the last couple of years that Anderson has considerably closed the gap. Since the beginning of 2010, his 109 Test wickets have come at an average of 23.74; his previous 148 had cost him 34.85 runs each. A comparison between the two thus only makes sense in the last two years, a period during which Anderson's consistency and his ability to excel under all conditions have improved significantly.

The biggest difference in Anderson's bowling is that he is no longer entirely dependent on the conditions to achieve his success. He has spoken about picking up the art of bowling with the scrambled seam to make his old-ball bowling more effective, and it shows in his numbers: over these last two years and a bit, Anderson averages 24 in his last five Tests in Asia, and 26 in Australia, both huge improvements on his earlier stats. In fact, Anderson's average in away and neutral venues has dropped from 45.63 to 26.65, an improvement of more than 41%. During this period, the home and away averages for both players are pretty similar: both have done better in home conditions, which isn't surprising, given that South Africa and England present conditions that are favourable for swing and seam bowling. However, both have impressive numbers overseas as well.

Test bowling records of Dale Steyn and James Anderson Bowler, period Tests Wickets Average Strike rate 5WI/ 10WM Steyn, career 54 272 23.18 40.9 17/ 4 Anderson, career 68 257 30.14 56.4 12/ 1 Steyn, since Jan 2010 20 100 21.84 42.5 6/ 1 Anderson, since Jan 2010 24 109 23.74 50.6 5/ 1

Steyn and Anderson, home and away, since Jan 2010 Bowler Home-Tests Wickets Average Away-Tests Wickets Average Dale Steyn 10 59 19.86 10 41 24.68 James Anderson 12 60 21.36 12 49 26.65

There are a few other fast bowlers who've done well during this period, but apart from the phenomenal Vernon Philander, none has achieved the kind of stats that Steyn and Anderson have. Philander has been exceptional, but he has only played seven Tests so far. Zaheer Khan is the only other bowler in the table below with a sub-25 average, but he has played only 15 Tests and taken 68 wickets during this period, compared to 100 and more by Steyn and Anderson.

The other factor that stands out in the table below is the dominance of South African and England bowlers - there are three from each team, which is proof that these two teams are the undisputed kings of fast bowling today. The three-Test series in England will thus also be about the support that the two leading strike bowlers will get from the rest of the attack.

Best averages for fast bowlers in Tests since Jan 2010 (Qual: 50 wickets) Bowler Tests Wickets Average Strike rate 5WI/ 10WM Vernon Philander 7 51 14.15 26.7 6/ 2 Dale Steyn 20 100 21.84 42.5 6/ 1 James Anderson 24 109 23.74 50.6 5/ 1 Zaheer Khan 15 68 24.72 46.0 2/ 1 Peter Siddle 16 60 26.18 50.3 3/ 0 Morne Morkel 20 78 26.53 51.7 4/ 0 Steven Finn 13 51 27.39 43.2 3/ 0 Stuart Broad 21 74 28.18 60.9 1/ 0

Back to the Steyn-Anderson discussion, though. While their overall stats in the last two years are pretty similar, a few differences emerge when comparing their stats against right- and left-hand batsmen. Anderson, as Kumar Sangakkara will testify, has been outstanding against left-hand batsmen, dismissing 39 of them at an average of less than 21 per wicket. The average isn't dissimilar to Steyn's against right-handers during this period (20.05). However, Steyn has had more problems against left-handers, just as Anderson has found it tougher to dismiss right-handers. That's only a relative term, though, as Steyn's average against lefties and Anderson's against right-handers are still pretty impressive.

Steyn and Anderson, against right- and left-handers in Tests since Jan 2010 Bowler v batsman type Runs Balls Wickets Average Scoring rate Steyn v right-handers 1564 3060 78 20.05 3.06 Anderson v right-handers 1750 3563 70 25.00 2.94 Steyn v left-handers 585 1200 22 26.59 2.92 Anderson v left-handers 814 1971 39 20.87 2.47

The big difference for Anderson is his hugely improved stats against left-hand batsmen. Till the end of 2009, Anderson's 45 wickets of left-handers had cost him more than 41 runs each. Over the last two years, though, he has found a far more probing line against them, as also the ability to move the ball late in the air. That has fetched him incredible success against them, with the average halving to 20.87.

Nowhere is the contrast more apparent than in his record against Sangakkara. Before 2010, he had bowled 129 balls to him in Tests, conceded 99 runs, and dismissed him just once. Since then, Anderson has dismissed Sangakkara five times in 96 balls, conceding less than ten runs per wicket. As his wickets break-up against left-handers shows, 14 of his 39 dismissals of left-handers were through catches to the wicketkeeper, and 18 more through catches, mostly in the slip cordon. Which means 32 of his 39 victims have been caught, most of them behind the wicket.

For Steyn, the stats aren't so startling: pre 2010, he averaged 17.83 against right-hand batsmen and 34.58 against left-handers; since then the gap in averages has narrowed, though numbers suggest he continues to favour bowling to right-handers.

Anderson v left-handers, before and since Jan 2010 Runs Balls Wickets Average Strike rate Before 2010 1865 3230 45 41.44 71.78 Jan 2010 onwards 814 1971 39 20.87 50.52

Anderson v Sangakkara, before and since Jan 2010 Runs Balls Dismissals Average Before 2010 99 129 1 99.00 Jan 2010 onwards 46 96 5 9.20

Anderson will want to settle scores with another top-class left-hander this summer in the home series against South Africa - Graeme Smith. Smith has so far dominated Anderson in Tests, scoring 357 runs in 534 balls for five dismissals, at an average of 71.40. Can the new, improved Anderson turn that head-to-head around on its head too, just as he has done with Sangakkara?

Meanwhile Steyn's relative discomfort against left-handers raises an interesting question, given that England's openers are both lefties. That small advantage, though, might be offset by the fact that England's middle order consists almost entirely of right-handers.

In these two years, Anderson also has a higher percentage of top-order wickets, with almost 24% of his victims being openers, and 66% being batsmen in the top six; the percentages are marginally lower for Steyn.

Since 2010, both bowlers have showed they're at the peak of their powers. With Test cricket's top spot at stake, both will have plenty of motivation to be at their best come July 19.

Top- and lower-order wickets for Steyn and Anderson in Tests since Jan 2010 Bowler Opener wkts Percentage Top 6 wkts Percentage Last 5 wkts Percentage Dale Steyn 20 20.00% 63 63.00% 37 37.00% James Anderson 26 23.85% 72 66.05% 37 33.94%

All stats for Anderson updated till the first innings of the ongoing second Test between Sri Lanka and England.