After the Brazilian's 79th minute strike, Andrea Esposito notched the equalizer for Lecce in the 93rd minute.
At the Via Del Mar, Milan had the chance to go up front on 12 minutes, when Kaka's shot was parried by Francesco Benussi in Marco Boriello's path but the latter hit the side netting from close range.
The hosts responded quickly through a Daniele Cacia long range shot which went just inches wide of Christian Abbiati's bar.
The visitors had another Boriello chance cleared off the line, after the striker chipped his shot past Benussi on 34 minutes.
The 26-year-old had an even better chance to score for Milan six minutes later. Boriello was one on one with Benussi but he lost focus and ran straight at the keeper.
After the interval, Milan's opportunities kept on coming. On 52 minutes Kaka was through on goal but fired his effort wide.
It wasn’t till the 79th minute when Milan finally scored. Substitute Alexander Pato had a perfect run with his first touch of the game before crossing to Ronaldinho who easily tapped in the Lecce net.
However, Lecce spoiled the night for their visitors on 93rd minute when Andrea Esposito raised above the Milan defense to head Andrea Zanchetti's header past Abbiati.
Despite the draw, Milan move to second in the table, level on 23 points with Napoli, while Lecce stay twelfth with 12 points.