CHICAGO – A self-proclaimed minister accused of trying to shake down slugger Gary Sheffield over a steamy sex video of his gospel-singing wife and randy R&B star R. Kelly first phoned the Yankees with an extortion bid, a team official claimed yesterday.

Testifying in federal court in Chicago, Yankee media representative Heidi Baker told jurors that Derrick Mosley phoned the team early last November about the raunchy tape that features DeLeon Richards in a sex romp with Kelly.

“A man said he had a videotape with Gary’s wife in a compromising position with a pop singer,” Baker said. “He asked me what it would be worth to the Yankees organization to have this tape.”

“He wanted something from us,” Baker said.

When Mosley asked what he should do with the video, Baker said she told him to contact the Sheffields’ business manager, Rufus Williams.

Mosley – who prosecutors claim first attempted to contact Richards by e-mail – is charged with demanding $20,000 to destroy the tape, which was made more than 10 years ago when the then-teenage gospel sensation was dating Kelly.

Williams, former chief financial officer for Oprah Winfrey’s Harpo Inc., said Mosley called him soon after his conversation with the Yankee media rep had ended.

“He told me that he hated to make this call” and that he had “some videotape of my client DeLeon Sheffield engaged in some really repugnant areas with R. Kelly,” Williams said.

He testified that Mosley also told him Richards had “to atone” for what was on the tape.

He said he was greatly concerned for Richards, whom he described as “a woman of God – the family is, always has been.”

Williams said he immediately contacted Richards, and the two agreed that they had to call the FBI.

Agents equipped him with a wire for a meeting with Mosley at the posh East Bank Club, and also taped two subsequent phone conversations.

During their recorded meeting, Williams said, Mosley stressed that he wasn’t as rich as Williams and “made mention of what he could have gotten if he had gone to the tabloids” with the videotape.

It was also during those talks that Mosley told Williams he wanted $20,000 to destroy the tapes – with the payment disguised as a fee for spiritual counseling for Richards to “make it appear legit,” prosecutor Clarence Butler told jurors in his opening statement.

Mosley even gave Williams instructions on how to wire him the money, Butler said.

“He knew of ramifications of what he had,” the prosecutor said. “This is just a scheme on the part of the defendant to commit extortion.”

Defense lawyer Michael Petro insisted his client is a community activist and “fighter for the little people,” not a con man.

“There was never any intent by Derrick Mosley to extort, blackmail or defraud anyone.

“Derrick Mosley was there to help, not to hurt,” he said in his opening remarks.

Sheffield is not expected to testify.

His wife – who looks directly at the camera and is clearly visibly on the torrid videotape – is listed as a prospective witness for Mosley, but the judge last week ruled she cannot be forced to testify.

Mosley has a rap sheet with arrests for bank fraud, passing bad checks, purse snatching and leaving the scene of an accident.

If convicted of extortion and fraud, he faces up to five years in prison.