Alberto Aquilani's brace was sufficient for the Azzuri to overcome their rivals, who put up a noticeable struggle.
Apart from giving his country a pivotal win, the promising midfielder netted his first goals on the international stage.
The AS Rome player scored an early opener on 8 minutes. Ten minutes later, Montenegro leveled when Mirko Vucinic scored from a successful counter attack
The world Champions regained the lead when the 24-year-old tucked in his second on 28 minutes to ensure first rank with 10 points.
Elsewhere, Robbie Keane scored a precious winner in Cyprus to help Ireland gain much-needed three points.
The Liverpool newly-signed hitman connected from point-blank range with Damien Duff's inch-perfect cross only five minutes after the kickoff.
Having scored, Keane has extended his Ireland all-time scoring record of 36 goals.
On top of that, Ireland laid to rest the ghost of their scandalous 5-2 loss to Cyprus, who had the upper hand for a while during the first half of Wednesday's game.
Second-placed Ireland are now trailing Italy by three points.
Earlier on the same day, penultimate Georgia drew 0-0 with Bulgaria in a dull match.