Amir (left), Asif (centre) and Butt face potential life bans if found guilty
By David Bond
BBC sports editor, in Doha
Pakistan Test captain Salman Butt told the International Cricket Council's spot fixing inquiry that he did not know how his agent had predicted with such accuracy when no-balls would be bowled in the Lord's Test match against England in August 2010.
Butt's evidence came as he and two other Pakistan players, Mohammad Asif and Mohammad Amir, pleaded not guilty to multiple charges of breaking the ICC's anti-corruption code, at a hearing in Doha.
In brief opening statements responding to the allegations, fast bowler Amir also told the three-man commission chaired by Michael Beloff QC that he did not know why businessman Mazhar Majeed told the News of the World when the no balls would be bowled.
But in a sign that divisions between the three players are already emerging, Asif took a different line, telling the tribunal that he bowled a no ball by mistake after being instructed by Butt to bowl a faster delivery.
DAVID BOND'S BLOG
Qatar is the scene for the most important inquiry cricket has staged since the King Commission into the Hansie Cronje affair 10 years ago
The players will be quizzed at greater length over the next two days with a verdict on the charges expected to be made by Sunday or Monday and punishments delivered afterwards, possibly by Tuesday.
The length of time set aside for the hearing reflects the weight of evidence the ICC is presenting to the tribunal.
On Friday it will hear from Mazher Mahmood, the News of the World journalist who broke the story.
The ICC is relying heavily on the newspaper's evidence, gathered as part of an extensive undercover sting last August.
And, although Pakistan coach Waqar Younis and one-day captain Shahid Afridi are also due to provide testimony via video link, it is the weight of cumulative evidence from the News of the World which the ICC believes will lead to all three players being found guilty of corruption.
If they are they found guilty of the more serious charges they could face bans from the sport of between five years and life.
Butt, Asif and Amir all sat through more than seven hours of evidence during the first day and are expected to be present for every day of the hearing, which is being held in the unlikely setting of Doha's financial district.
The case could not be heard in Dubai, where the ICC is based, as Asif is barred from the country because he has been banned in the past for doping offences which contravene Dubai's rules on entering the country.
Intriguingly, there were also reports on the website Cricinfo - which the ICC did not confirm or deny - that a request by the Pakistan Cricket Board to be observers at the hearing was rejected by two of the three players, a sign perhaps of the tension between the cricketers and their governing body.
With the ICC under pressure to protect the sport's integrity at a time when it is under threat from illegal betting in India and elsewhere, the governing body is well aware of the importance of this case.
It is the first time the ICC has mounted an anti-corruption inquiry of this nature as its anti-corruption code is relatively new.
Previous inquiries were carried out by the domestic cricketing and judicial authorities.
Sharad Rao, Kenya's former attorney general and a member of the three-man commission, summed up the significance of the inquiry when he told reporters before the start of the hearing: "It is an important hearing for the future of cricket."
With the ICC aware that cricket's reputation is also in the dock, they want the panel to hand out lengthy bans to the players in the hope it will send a strong message to the rest of the sport