Projections based on very early results suggest Premier Silvio Berlusconi's candidate for mayor in Milan is locked neck-and-neck with her opponent.
The Milan race was among the most significant in two days of local voting seen as a test of popularity for the scandal-hit Italian leader.
The projections released Monday by state TV RAI were based on only 5 percent of the sample and had a margin of error of plus or minus four percentage points.
Berlusconi's candidate was at 44 percent and her rival at 45 percent.
If confirmed, the result would force a run-off in two weeks. It would be seen as a blow to Berlusconi, whose power base is in Milan and whose coalition has run the city for several terms. Berlusconi campaigned relentlessly ahead of the vote.