Saturday's 2-0 win in Georgia came courtesy of two own goals from AC Milan defender Kakha Kaladze and, discounting his double calamity, the European Group Eight leaders have not scored in four games.
Playmaker Andrea Pirlo is suffering an alarming dip in form while the world champions lack a player who can burst from midfield to aid the strikers.
However, coach Marcello Lippi is concentrating on qualifying for South Africa next year rather than panicking about form.
"I'm absolutely not worried about goals, because what counts is that we get it in the net whatever way," he told reporters.
A win over the East Europeans in Turin would send Italy four points clear at the top and leave them needing just a point away to second-placed Ireland in October to go through.
The winners of the nine European groups qualify directly for South Africa and the eight best runners-up play off amongst themselves for four more places.
De Rossi would be the obvious candidate to come back in on Wednesday given his bustling approach, which may give Italy some extra bite even if the goal threat is still missing.
Italian media, shocked at defeats by Egypt and Brazil at June's Confederations Cup, have rattled World Cup winner Lippi for the first time with their constant questions about why Sampdoria's Antonio Cassano is not in the squad.
Asked who had been Italy's "fantasy player" against Georgia in the absence of the creative Cassano, an honest Lippi replied with the name of goalkeeper Gianluigi Buffon.
Juventus midfielder Claudio Marchisio hopes to shake off a thigh injury in time for Wednesday but he has not yet established himself as the box-to-box player Italy need.
Bulgaria, who beat Montenegro 4-1 on Saturday, held the Azzurri to a goalless draw in Sofia last October but need to win to realistically keep their World Cup dream alive.
"It'll be a tough game against Italy but we're more confident after the Montenegro match and I think we have the strength to win," said striker Dimitar Berbatov, who ended his one-year international goal drought on Saturday.
Stanimir Stoilov's men could field the same side in Turin unless defender Zhivko Milanov recovers from a knee problem.
Probable lineups:
Italy: 1-Gianluigi Buffon; 2-Gianluca Zambrotta, 5-Fabio Cannavaro, 4-Giorgio Chiellini, 3-Domenico Criscito; 7-Marco Marchionni, 10-Andrea Pirlo, 6-Daniele De Rossi, 8-Mauro Camoranesi; 11-Giuseppe Rossi, 9-Vincenzo Iaquinta
Bulgaria: 1-Dimitar Ivankov; 7-Stanislav Manolev, 5-Kiril Kotev, 3-Iliyan Stoyanov, 2-Radostin Kishishev; 10-Stilian Petrov, 6-Stanislav Angelov, 8-Chavdar Yankov, 17-Martin Petrov; 18-Dimitar Berbatov, 16-Dimitar Rangelov
