After topping the world run-scoring list for two years running, Michael Clarke has suffered a rare slip in form leading into South Africa.

Michael Clarke has never felt higher in his career but, if he fails in the first Test in South Africa next month, the Australian captain will equal the worst scoring streak of his career.

Clarke has failed to reach 50 in his past seven innings, which is the third lowest run of his 102 Test matches.

He went nine innings without a half-century between November 2004 and July 2005 and again between September 05 and April 06 during which time he was dropped for the only time in his illustrious career.

But despite failing to pass 30 in the last seven innings of Australia’s 5-0 Ashes clean sweep this summer, Clarke still averaged 40.33 after scoring crucial hundreds in Brisbane and Adelaide when the series was on the line.

Australia have rarely succeeded when Clarke has failed, and he’ll be relied on to break his drought in the first Test against the world No.1 side South Africa in Centurion in early February.

Coach Darren Lehmann is concerned about Australia’s repeated first-innings stumbles during the Ashes series, and Clarke is the centrepiece of the batting order at No.4.

“He’s our best batsman, first and foremost, and he needs to make runs,” said Lehmann, following the Sydney Test.

“He’s certainly done that over the period of time of these 10 (back-to-back Ashes) Test matches.

“We’ve got to improve our first-innings batting … again we were 5-97 (in Sydney), so we’ve got to improve when we come up against South Africa away from home.”

What’s bizarre about this mini-slump is that Clarke wouldn’t appear to be in a slump at all.

In fact, he’s only averaged less than 40 in one tour since taking over as skipper – in the West Indies in 2012.

Clarke has been the world’s top run-scorer for the past two years running – piling on 1093 in 2013 and, during the Melbourne Test, he passed the 8000 runs barrier.

The most emphatic whitewash in Ashes history was the crowning achievement of Clarke’s career, with his dynamic captaincy crucial in Australia’s domination of England.

“As a leader, on and off the field, he’s exceptional. On the field, tactically, he’s one of the best captains I’ve seen,” Lehmann said.

“Off the field … in England, with how we wanted to change, he’s driven that.”

Clarke is his own harshest critic and will be hungry for a return to form.

He scored arguably the finest century of his career against Dale Steyn, Morne Morkel and Vernon Philander in treacherous conditions when he was last in South Africa in 2011. However, the personal achievement was hugely overshadowed by the fact he was captaining a side that was rolled for just 47 runs in Cape Town.