Four-time NBA champion Shaquille O'Neal has announced his retirement on twitter after a professional career spanning nearly two decades.

Four-time NBA champion Shaquille O'Neal has announced his retirement on twitter after a professional career spanning nearly two decades.

The 39-year-old also posted a video on a social media website after deciding his battle with injuries had gone on long enough particularly in the latter stages of his career with the Phoenix Suns, Cleveland Cavaliers and Boston.

A spokesman for the Boston Celtics - O'Neal's current team - said the player had not notified them of his plans.

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