Sri Lanka off spinner Muttiah Muralitharan, who became Test cricket's highest wicket-taker after claiming his 521st victim on Saturday, is the world's most successful and controversial bowler.

Imparting prodigious turn through a unique combination of finger spin and wrist rotation, Muralitharan reached 521 wickets to surpass former West Indian fast bowler Courtney Walsh's mark of 519.

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Muralitharan had gone into the match against Zimbabwe with 513 wickets, needing seven more to pass Walsh's record.

After grabbing six wickets for 45 in the host's first innings, the scalp of Mluleki Nkala in Zimbabwe's second innings handed him the record. He took one more wicket to finish with two for 27 from 8.1 overs.

On the way to claiming the landmark wicket, he overtook Australia's Shane Warne who has 517 victims from 110 Tests.

"Murali" has achieved the feat in only 89 Tests compared to 132 for Walsh, who retired in 2001.

At Test level, Muralitharan has a best innings return of nine for 51 and a match haul of 10 wickets or more on a world record 13 occasions.

Still only 32, Muralitharan has vowed to play on until the 2007 World Cup and wants to become the first bowler to take 600 wickets.

However, his career has been troubled by suspicions over the legality of his unconventional bowling action.

He was called for throwing during tours to Australia in 1995-96 and 1998-99 and his bowling action has been likened to that of a javelin thrower by former India left-arm spinner Bishen Bedi.

While the world's governing body cleared his action following extensive bio-mechanical research on both of those instances, he was again reported for a suspect action two months ago after the conclusion of Australia's tour to Sri Lanka.

A report on the legality of his 'doosra' delivery is yet to be published.

FLEXIBLE WRIST

Following investigations into the two earlier instances, scientists concluded that a congenital disability prevented his bowling arm from fully extending, coupled with an abnormally flexible wrist, created the optical illusion of throwing.

The controversy proved to be the turning point of his career as the overwhelming support of his team mates swelled the confidence of a previously shy character.

Prior to the 1995-96 tour to Australia, Muralitharan had been reluctant to experiment with his bowling but afterwards he unveiled a range of new variations, including a top spinner and a leg spinner.

During the first three years of his career, he had averaged four wickets a Test. But since being called for throwing in Melbourne in 1995, Muralitharan has averaged an incredible 6.65 wickets in 66 Test matches.

The son of a hill-country confectioner, Muralitharan learned to play the game at St Anthony's College, a private boarding school run by Benedictine monks.

IMMEDIATE SUCCESS

As a 14-year-old, he aspired to becoming a fast bowler but his small frame and faltering action left him fighting for a place in his school team.

His coach there persuaded him to switch to off spin with immediate success and, during his final year, his record-breaking exploits began as he took the most wickets in a single season by a Sri Lankan schoolboy.

His talent was quickly spotted at higher levels and, aged 19, he moved to Colombo with his sights set on pursuing a career in cricket.

After just three first-class games, he was selected for the Sri Lanka A tour of England in 1991 and made his Test debut in Colombo a year later against Australia, claiming three wickets in the match.