Greer is the only uncapped man in Gordon Strachan's squad to face Croatia in their World Cup qualifier at Hampden Park on Tuesday after he was forced to drop out of the squad for the 1-0 win in the reverse fixture in June with tonsillitis.
The 32-year-old had played twice for Scotland B during his time at Rugby Park before securing a move to then League One side Doncaster in 2009.
It looked as though his chance of international honours had passed as he missed out on selection for the national side at the Keepmoat Stadium and after joining Swindon.
But his club career has been rejuvenated by a successful spell on the south coast with Brighton, where he was part of the squad that made it to the Championship play-offs last season, and Strachan has rewarded him with another call-up.
"When I left Kilmarnock to go down south I thought that was it for me," he said.
"I went to play at Doncaster at League One and I thought that was too low to get called into the Scotland squad but since then I have moved to Brighton in the Championship, so we will see what happens in the future.
"The new manager came in, he has his own ideas so in the back of your mind you think hopefully this manager will like me and I will have a chance.
"You strive all your life to play for the national team and I was obviously delighted to get called up the first time.
"We had finished for the season when I got called up for the Croatia game and I was gutted that I couldn't stay due to illness.
"It is up to me now. It is up to me to train well when I am here, hopefully impress the manager and hopefully get a chance."
Greer is likely to start on the bench against Croatia with Strachan likely to stick with the defensive pairing of Russell Martin and Grant Hanley but he is content to wait for his opportunity to impress.
"You don't really tinker that much with the back four and the keeper, unless there is an injury or someone gets sent off, so you wait until your chance comes," he added.
"I am happy to be here and I will train well and hopefully if I continue to do that I will get an opportunity at one point."