Cesare Prandelli's men lead Bulgaria, who they face in Palermo on Friday night, by four points in Group B while the Czech Republic are a further point off the pace ahead of Tuesday's meeting in Turin.
Six points from the double-header would leave Italy untouchable on 20 points and making travel plans for another summer in Brazil after their promising third-placed finish in the Confederations Cup.
And Sunderland winger Giaccherini is urging his colleagues to render October meetings with Denmark and Armenia meaningless before the domestic schedule starts to become a serious distraction.
He told figc.it: "People always say that September is a hard month for the national team but I think everyone's in good shape.
"But Bulgaria are much further along in their domestic league than we are and caused us a lot of trouble over there a year ago.
"The goal is to qualify for the World Cup as soon as possible. We have two home games and they'll definitely be difficult.
"We have to get two good results so we're able to go into the last few games without any nerves."
Veteran goalkeeper Gianluigi Buffon will match retired defender Fabio Cannavaro's record of 136 appearances in Azzurro should he feature in both games, but he is more concerned with keeping ambitious Bulgaria under wraps in Sicily.
"We need to approach this game with a lot of care and attention so we can take another step forward," the Juve keeper said.
"Bulgaria are an organised team who know how to approach this kind of game, they know how to defend and how to hit you on the counter-attack."
Southampton striker Pablo Osvaldo is suspended at the Stadio Renzo Barbera, along with AC Milan duo Riccardo Montolivo and Mario Balotelli.
As much as Bulgaria coach Lyuboslav Penev would like to overtake Italy at the top of the group, his realistic target remains securing the play-off place from the chasing pack.
He said: "Maybe mathematically, if we win three matches then we will go to the play-offs.
"But let us first do a job against Italy before we think about Malta, then Armenia and finally the Czech Republic.
"The players all know what is expected of them and they know it won't be easy. There are some very tough games ahead of us, three overseas and only one at home."
The Lions boast two of the group's top scorers with PSV Eindhoven midfielder Manolev and Aston Villa winger Aleksandar Tonev tied on three goals each.
Michal Bilek's Czech Republic side are plotting to snatch the play-off spot from Bulgaria, however, and they welcome fourth-placed Armenia to Prague having beaten them 3-0 in Yerevan.
Bottom side Malta need at least seven points from their remaining four games, and a serious collapse from the leading nations, to have any chance of qualifying, and coach Pietro Ghedin knows a wounded Denmark side will not roll over at Ta' Qali.
The Danes were humbled by Armenia in their last qualifier, losing 4-0 at home, before slumping to 3-2 friendly defeat to Poland last week.
Ghedin feels his islanders could feel the sting of a backlash, telling the Times of Malta: "They will be determined to get a good result, more so after losing their last two matches."
Malta picked up their first competitive win away from home in 20 years before the summer break - beating Armenia 1-0 in Yerevan through Michael Mifsud.