Antonio Nocerino and Zlatan Ibrahimovic scored second-half goals as AC Milan defeated Siena 2-0 on Saturday to knock Juventus off the top of Serie A. Milan now have 31 points, one ahead of Juventus who can reclaim pole position when they tackle struggling Novara on Sunday. Milan dominated the first half but had to wait until the 54th minute to clinch the breakthrough when Robinho created the opening for Nocerino to score his sixth goal of the season. Ibrahimovic added the second nine minutes later courtesy of a controversial penalty. It was the big Swede's 10th goal of the season and fifth from the spot, but was awarded  only after Kevin-Prince Boateng theatrically collapsed to the ground under a challenge from Zeljko Brkic. Ibrahimovic has now joined Antonio Di Natale of Udinese in second place on the goal scorers chart, one behind Atalanta's German Denis who has 11. Siena's main threat came from midfielder Francesco Bolzoni, who had chances in the 23rd and 78th minutes. They are fourth from bottom and could slip into the botton three on Sunday if Cesena, with Adrian Mutu on a hot streak of three goals in four matches, defeat Inter Milan. "After the break and our opening goal, it was much easier," said Milan coach Massimiliano Allegri. "Tonight was not an easy game and it was important to get the three points. When you play badly and still win, it’s a good sign." Allegri also backed Nocerino to keep scoring. "I hope he gets to 15 goals. He has already got six and is proving he is a player who belongs at Milan." Denis thought he had given Atalanta a 2-1 win at Fiorentina on Saturday when he found the target in the 86th minute, but the home side rescued a point in a 2-2 draw when Montenegro star Stevan Jovetic levelled two minutes from time. Fiorentina had taken a ninth-minute lead when Alberto Gilardino scored his second goal of the season with a fine volley from a cross by Peru international Juan Manuel Vargas. But Atalanta made it 1-1 through Andrea Masiello in the 81st minute with Argentina star Denis giving his side hope of three points four minutes from the end.