Sirigu was part of the Italy squad that lost 1-0 to Spain in a midweek friendly while the majority of league-leading PSG's players were on duty with national sides around the world.
The 27-year-old is therefore worried preparations for a tricky trip to Corsica have been disrupted.
"It is always difficult to prepare for a game when players are still returning from international duty," he told psg.fr.
"Lots of us have been on the move and so we've not trained together. That means the trip to Bastia will be even more difficult.
"I think we will now have to give 100 per cent to prepare for this match.
"We cannot think of our national teams but we must go back to how it was after our match against Marseille (PSG won 2-0) and act as if we'd never gone away.
"The focus should be on Paris Saint-Germain."
The reigning champions could pull 11 points clear at the top with victory at the Stade Armand Cesari, should Monaco slip up at home to struggling Sochaux.
Claudio Ranieri's men suffered a 2-0 defeat at St Etienne last time out and defender Ricardo Carvalho is demanding an immediate response.
He told Monaco's website: "After the loss it's very important for us to play better and win against Sochaux.
"A great team always reacts well to setbacks.
"We will give everything to the very end, always with the aim of qualifying for the Champions League."
In third place are Lille, who host 2012 champions Montpellier, while St Etienne could take the last Champions League place by bettering Les Dogues' result when they visit Lorient.
Marseille are in fifth place and eager to bounce back from their Classique defeat to PSG with a positive result against south-coast rivals Nice on Friday night.
Ready to pounce should L'OM falter at the Allianz Riviera are Europa League hopefuls Bordeaux and Lyon, who face off in the Gironde region.
The battle for survival is heating up and Nantes - this week slapped with a 16-month transfer embargo - could pull further away from the relegation zone with a home victory over basement boys Ajaccio.
In 18th place and five points from safety are Valenciennes, who host 14th-placed Rennes, with Guingamp entertaining an Evian side who occupy the last safe spot.
VA goalkeeper Magno Noaves said: "For sure the situation is delicate.
"We are five points behind and it will mean we have to put a lot more commitment into tackles and have more desire to win matches."
Elsewhere, inconsistent Toulouse welcome surprise package Reims - currently occupying seventh place thanks to a run of three wins in four games - to the Stadium Municipal.