Udrih suffered the injury after playing just six minutes in the first half of Miami's 101-93 overtime victory against Indiana on Monday. The Heat announced during Monday's game that an X-ray on Udrih's foot was negative, but according to sources, a follow-up MRI exam on Tuesday revealed he needed surgery.
Heat coach Erik Spoelstra declined to reveal details about the injury after Tuesday's practice.
The Heat on Wednesday said Udrih is expected to miss three months.
Udrih's absence leaves starter Goran Dragic as the lone experienced point guard on the roster. The Heat have already lost reserve guard Tyler Johnson to shoulder surgery and are also without leading scorer Chris Bosh, who is sidelined indefinitely with an undisclosed medical condition.
With Udrih out, the backup role now will partly fall to rookie Josh Richardson.
"He understands what we're looking for,'' Spoelstra said earlier Tuesday of Richardson, speaking before the Udrih news was known. "He fits defensively on that side of the floor already.''
Udrih was acquired by Miami in a November trade that sent Mario Chalmers to Memphis. In 36 games with the Heat, including five starts, Udrih has averaged 4.4 points, 2.5 assists and 1.8 rebounds.
Information from The Associated Press was used in this report.