In a courtroom gamble that could determine his fate, Ebbers, 63, will have the chance to tell his side: Defense lawyers are expected to call him to the stand Monday as the trial opens its sixth week.
Sullivan has testified that Ebbers repeatedly instructed him to "hit our numbers" - a statement Sullivan said he interpreted as a command to commit fraud.
Prosecutors say Ebbers, worried about $400 million in personal loans backed by WorldCom stock, ordered false revenue and earnings numbers to be presented to Wall Street to bolster WorldCom's stock price.
Calling Ebbers represents a huge risk for the defense. Although the move allows Ebbers to tell his version of the scandal directly to the jury, it also opens him up to a potentially damaging cross-examination.
The strategy is unpredictable. Former Tyco International Ltd. lawyer Mark Belnick was acquitted of grand larceny charges after taking the stand in 2004 - but ex-Wall Street banker Frank Quattrone was convicted of obstruction after he testified.
The defense notified Judge Barbara Jones on Friday that it planned to call Ebbers as a witness. On Thursday, defense lawyers told reporters the trial could wrap up this week - but would not say whether Ebbers would testify.
Other defense witnesses have included Bert Roberts, a former WorldCom chairman who said Sullivan told him in 2002 that Ebbers was unaware of the improper accounting entries made in WorldCom's books.
WorldCom was driven into the largest bankruptcy in U.S. history when fraud was revealed in 2002. It has since re-emerged under the name MCI Inc., with headquarters in Ashburn, Va.
The nine counts against Ebbers carry up to 85 years in prison.
By Erin McClam