NEW YORK (AP) – Bernard Ebbers took the stand at his trial Monday and flatly denied any role in the $11 billion accounting scandal that sank WorldCom, telling jurors his “marks weren’t too good” in school and that he knows very little about accounting.

The former WorldCom CEO said he fancied himself as “coach” of the company and left the numbers-crunching to former finance chief Scott Sullivan.

Under questioning from his top lawyer, Ebbers explicitly refuted earlier testimony from Sullivan, who claimed that Ebbers pressured him to cook the books to meet Wall Street expectations.

“I wasn’t advised by Scott Sullivan of anything ever being wrong,” Ebbers said. “He’s never told me he made an entry that wasn’t right. If he had, we wouldn’t be here today.”

The matter-of-fact denial was perhaps the most dramatic moment to date in the five-week-old trial of Ebbers, who is accused of orchestrating the accounting fraud that plunged WorldCom into the largest bankruptcy in U.S. history in 2002.

Placing Ebbers on the witness stand to defend himself represented a huge gamble for the defense. Ebbers later was to be cross-examined by prosecutors.

In three hours of testimony Monday morning, Ebbers was clear and plainspoken, addressing his lawyer as “sir” and occasionally displaying a laid-back, folksy Southern temperament.

Ebbers admitted he was a demanding and sometimes temper-prone boss at WorldCom, but repeatedly said he was unfamiliar with the details of finances and accounting.

Ebbers said he has never taken an accounting course and that even as his company grew into a telecommunications giant, he knew little about technology.

“I know what I don’t know,” Ebbers testified. “I don’t, to this day, know technology. I don’t know finance and accounting.”

In fact, Ebbers said he once considered retiring as CEO in 2000, as the operations of the company became ever more complex, saying he was “embarrassed” after a meeting with BP Amoco officials in London about a deal.

Ebbers’ statements conflict with testimony by Sullivan, who described Ebbers as a detail-oriented manager who was much more familiar with accounting than most CEOs he encountered.

Ebbers also told jurors about bouncing between colleges earlier in life because of “my marks weren’t too good” and said he enjoyed both playing and coaching basketball for high school and small colleges.

Ebbers said he made a foray into the motel management business early in his career and said he was extremely cost-conscious, even irritating some customers by requiring them to pick up and drop off towels at the front desk.

In 1983, he joined with partners to start a small long-distance service in Mississippi, gradually building it into the global giant WorldCom, which bought MCI in 1998.

The central issue in the trial so far remains whether jurors believe Sullivan told Ebbers that the only way to meet Wall Street estimates would be to falsify the books.

Sullivan has said he repeatedly told Ebbers that such actions were wrong, but has said Ebbers came back with the refrain, “We have to hit our numbers.”

Ebbers is charged with fraud, conspiracy and making seven false filings to the Securities and Exchange Commission. The charges carry up to 85 years in prison.