The extent of this latest injury is not yet clear but its expected that Pahars will be forced to sit out Saints game against Chelsea.
"I had a message to say he has hurt his right groin but I do not know how bad it is until I see him," physio Jim Joyce told the clubs official website.
"He sounded distraught on the phone but it could just be an initial panic - we just don't know until we have a proper look.
"Last time he came off playing for Latvia, he was training again six days later. If he came off last night then we presume he is a doubt for Saturday.