The move comes on a whirlwind day for the Mavericks.
A three-year deal worth in excess of $9 million for former Mavericks guard Devin Harris fell apart after X-rays unexpectedly revealed that the veteran has a dislocated toe on his left foot, according to sources close to the situation.
In addition, first-round pick Shane Larkin suffered a broken ankle during Friday's summer league practice, and the point guard is expected to be out three months.
The money no longer committed to Harris, sources said, has been earmarked for a starting center, with free agent center Samuel Dalembert clearly ranking as Dallas' No. 1 target.
Ellis averaged 19.2 points and 6.0 assists for Milwaukee last season. He rejected a contract extension from the Bucks that would have enabled him to make $36 million over the next three years.
Frustrated with talks in free agency, Ellis parted ways with his longtime agent, Jeff Fried, on Wednesday.
Information from ESPN The Magazine's Chris Broussard and ESPNDallas.com's Tim MacMahon was used in this report.