ROME - Italy forward Antonio Di Natale is set for a long spell on the sidelines after damaging ligaments in his left knee in Saturday's 2-0 win in Montenegro. The Udinese player suffered the injury at the start of Group Eight World Cup qualifier when he fell awkwardly on the slippery surface. "The recovery time will vary depending on a decision that will be taken in the next few days," national team doctor Enrico Castellacci told the Italian football federation's website. "The doctors will have to decide whether to use conservative therapy or operate." It is the latest in a string of injury blows for Italy coach Marcello Lippi, who was already without a host of regulars, including forwards Luca Toni and Alberto Gilardino. Italian media said Lippi does not intend to call up a replacement for Di Natale for Wednesday's clash with Ireland in Bari, who are two points behind the world champions in second place in the group.