Mystery surrounds the illness which has laid low West Indian super batsman Brian Lara in the third cricket Test against Australia here.

Lara left his sick bed on Saturday's third day and came in down the batting order at number eight to try and get the West Indies past the follow-on, but was out controversially five overs from stumps for 14.

Lara laboured during his 80 minutes at the crease, but he and Windies team officials would not say what was wrong.

Team officials would not say whether the premier batsman might have contracted chicken pox, which kept teammate Jermaine Lawson out of the second Test.

Lara, who celebrated his 34th birthday on Friday, arrived at

Kensington Oval after tea and left without explanation about his condition.

"You've got to go to the team manager. I batted today and I will bat in the second innings," Lara

said late Saturday.

But team manager Ricky Skerritt added to the general confusion when he said: "I'm not the

team doctor. I'm not going to talk about Lara."

A team spokesman said Lara's health would be assessed again during Sunday's fourth day.

The latest setback continues Lara's recent health problems. He contracted hepatitis late last year, which forced him out of the tour to India last October and out of international cricket for four months.

Lara was hospitalised after scoring a century during the Champions Trophy in Sri Lanka last September and he did not play for the Windies again until February's World Cup.

Lara's situation is critical to the West Indies' attempts to prevent a first-ever series whitewash in 73 years' cricket in the Caribbean.

He will have only a few days to recover before Friday's fourth and final Test in Antigua.

Lara has been the Caribbean's great batting hope with centuries in the opening two Tests of the series against the powerful Australian bowling attack in Guyana and Trinidad.