Boruc has not played a competitive game for Poland in two and a half years but could return to the side for their World Cup qualifier against Ukraine on Friday after impressing for the Saints this season.
Szczesny, on the other hand, has suffered a downturn in form at Arsenal which has seen him dropped by Arsene Wenger for their last two games, with fellow Pole Lukasz Fabianski stepping in.
Asked who was currently playing better out of him and Boruc, Szczesny told Przeglad Sportowy: "Definitely Artur Boruc.
"Since February, my situation has changed. I have had a drop in form."
Szczesny admits he does not know who coach Waldemar Fornalik will choose between the sticks in Warsaw on Friday night.
"It is not settled who is first choice," he added. "It's hard to speak about this, because I do not know if I'll play. I haven't come here as a back-up.
"My goal is simply to try and get a place in the first-team."