All Blacks lock Ali Williams' rugby season is virtually over with news he will require a third operation on his troublesome achilles tendon.

All Blacks doctor Deb Robinson said Williams would be sidelined until the end of the year after originally targeting a comeback in the New Zealand provincial championship which starts in July.

Williams, who turned 29 on Friday, ruptured the tendon during a pre-season match for the Blues in January and had been suffering unexpected pain in recent weeks.

A follow-up scan in Auckland on Thursday revealed further damage to his tendon.

"The scan showed that, while the surgical procedure to connect the tendon to his joint remains intact, it has caused a partial tear further up his tendon," Robinson said in a statement.

As a result, Williams will require a third operation which will involve a reconstruction of the tendon.

"It's obviously a frustrating and distressing time for Ali but throughout his setbacks over the last year he has remained optimistic about his situation and is keen to overcome his injuries and get back on the rugby field," Robinson said.

Williams missed the entire All Blacks season last year, largely due to achilles tendon problems.

The most recent of his 61 Tests was the 32-6 win over England at Twickenham at the end of 2008.

All Blacks coach Graham Henry said: "Everyone involved in the All Blacks feels for Ali and we will continue to give him our full support as he goes through further surgery and rehabilitation."

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