Bertrand disappointed by England omission
The left-back joined the south-coast club on loan from Chelsea in July and has played in all 11 of their Premier League games this season.
Bertrand has received much praise for his performances from Southampton manager Ronald Koeman, who has made a flying start to his tenure with a side that currently sit second in the English top flight with 25 points.
Despite the positive reviews from Koeman, Bertrand was snubbed by England boss Roy Hodgson for the upcoming Euro 2016 qualifier with Slovenia and friendly with Scotland, a decision that has left the 25-year-old deflated.
"It will be quiet here in Southampton these next two weeks," Bertrand said. "But it's a chance for those of us who are left out, like me, to work on things and come back flying again.
"I'm very disappointed. I've started very well this season, we're second in the league, so I don't know what the criteria is to get in there at the minute.
"I would love to get another chance but, at the end of the day, it's not down to me. I feel like I should have achieved that already, so hopefully it will come."
Bertrand has two England caps, his last coming in the 2014 World Cup qualifier with Ukraine back in September 2012.