Alberto Gilardino's first-half goal, coupled with some fine saves from captain Gianluigi Buffon, secured victory against Bulgaria to give Cesare Prandelli's men breathing space at the top of Group B.
Gilardino headed in a perfect left-wing cross from Antonio Candreva seven minutes before the interval but the Azzurri needed a great performance from their goalkeeper to earn three points against a strong Bulgaria side in Palermo. The Italians now sit seven points clear of Luboslav Penev's second-placed side with three games to play.
Missing the suspended Riccardo Montolivo, Pablo Osvaldo and Mario Balotelli and with Claudio Marchisio and Andrea Barzagli absent due to injury, the Azzurri struggled in the early stages with Todor Nedelev and Stanislav Manolev testing Buffon from distance.
Lorenzo Insigne did the same for Nikolay Mihaylov at the other end but the Bulgaria goalkeeper could do nothing when Gilardino headed in from close range in the 38th minute. The hosts posed more danger from the same flank soon after but Mihayloy managed to palm away Luca Antonelli's shot.
That did not compare with Buffon's heroics after the break as he produced an improbable stop to deny Ivelin Popov from point-blank range. The skipper made another diving save to keep out Dimitar Rangelov's header while Medelev's low shot from inside the penalty box flashed just wide of the right post.
A mix up between Mihaylov and Nikolay Bodurov almost led to Gilardino's second but the defender made amends to slide in and block the striker's shot. Bulgaria pushed hard until the final whistle and went close with the last touch of the game but Yordan Minev missed the target with a close-range header. Italy could book a place in Brazil on Tuesday with victory against the Czech Republic in Turin, when Buffon could move level with Fabio Cannavaro as the Azzurri's most-capped player.