Although no settlement was reached, sources said the two men had a "friendly conversation" for about 90 minutes at Sterling's house in Beverly Hills in their first face-to-face meeting since Ballmer negotiated the record-setting sale with Shelly Sterling on May 29.
Donald Sterling has since challenged his wife's authority to sell the franchise in state court.
Last week NBA commissioner Adam Silver said he wasn't sure a new owner would be in place by the start of next season, as Donald Sterling has vowed to fight his termination and the sale of the team.
The original agreement called for the sale to close by July 15, with a possible extension to Aug. 15. The NBA has the option of resuming termination proceedings and subsequently selling the team itself if the sale is still in limbo by Sept. 15.
The meeting was arranged Sunday night after a three-hour meeting earlier in the day between Donald and Shelly Sterling, sources said.
Donald Sterling had been preparing to file a new suit in state court on Monday morning before he and his wife spoke at length Sunday night at his house.
He then asked to meet with Ballmer after the meeting with Shelly Sterling and a meeting with his attorney, sources said.
While Sterling famously called his wife "a pig" after she testified in the civil case against him two weeks ago, he was emotional when speaking about his love for her during his own testimony.
Shelly Sterling is due to testify again in the civil suit between the Sterlings on Tuesday. At issue in that case is whether she was authorized to sell the franchise to Ballmer.
Her attorneys contend that she followed all of the procedures outlined in the Sterling Family Trust -- which owned the team and the other assets the couple has accumulated -- when two neurologists examined her husband and determined he was mentally incapacitated and unfit to conduct his own legal and business affairs. The two experts testified in court that Donald Sterling showed the onset of Alzheimer's disease.
Donald Sterling and his attorneys dispute that, arguing the exams were conducted under false pretenses because he was not informed the results could later be used to exclude him as a trustee. His lawyers also argue the doctors violated federal privacy laws by disseminating the results of his exams to attorneys in the case, and that their testimony and findings should not be admissible.
That argument was struck down by Judge Michael Levanas last week.
However, Sterling's attorney's had also planned to argue that the sale should be canceled after he revoked the trust on June 9.
Shelly Sterling's attorneys argued she had a fiduciary responsibility to complete the sale even after the trust was revoked, citing the legal and financial fees the trust would incur if the team was sold by the NBA. They also cited $480 million in loans that became due, once the trust was revoked.
In his own testimony two weeks ago, Donald Sterling said he believed his wife agreed to sell the Clippers only because she was "terrified and frightened of this NBA" and that if he were to sell the franchise himself, he could get $2.5 billion to $5 billion because of a boom in media-rights fees.
He vowed to fight the NBA for as long as it took to prove his point.
"Do you think Microsoft is foolish? Do you think they don't think and wonder where they're going to get the money back?" Sterling said. "There's no ego involved here. There's tremendous opportunity."