McCallum made 181 in the Intercontinental Cup this year

The Scots play warm-up matches with Bangladesh and Zimbabwe this weekend but have India and Pakistan in their group in the main competition.

"Anything can happen, it's such a short game," 29-year-old McCallum said.

"If early wickets or a good innings put sides on the back foot there is no reason why we can't cause an upset."

McCallum, who is being given time off from his duties as a PE teacher at George Watson's School in Edinburgh to play in South Africa, is no stranger to facing the sub-continent super powers.

He made 58 on his one-day international debut against a Pakistan attack led by Mohammad Asif and Umar Gul and also featuring spinners Danish Kaneria, Shahid Afridi and Shoaib Malik in 2006.

Then against India including Ajit Agarkar, RP Singh and Munaf Patel at Glasgow in August he hit three fours and a six in 41 before he was dismissed by spinner Piyush Chawla.

"We will look to take them on, whatever they throw at us. It's going to be a fantastic opportunity to have a go at these guys," he said.

"There will be huge crowds at the games and with two big nations like Pakistan and India against us it will be a fantastic challenge - one we're all looking forward to.

"Our best results by far in the last couple of years have come against some of the county sides when we've had reduced-overs matches, so we're looking forward to playing the shorter version of the game and, who knows, on the day we might be able to upset them."