"It is a special feeling," Kallis said. (Agencies)
"It's strange walking out to bat knowing that there is no tomorrow and it will be your last opportunity to get a hundred for your country," the 38-year-old added.
The legendary cricketer, playing his 165th Test, notched up the 45th century of his career on day four of the second cricket Test against India on Sunday.
Kallis scored 115 runs off 316 balls with the help of 13 boundaries to South Africa his to a commanding position in the ongoing match.
"It's a different kind of pressure, being in the nineties for the last time was different to normally being in the nineties. At least I could fall back on my experience and managed to get the three figures," he said.
In the process, Kallis (13,289) also became the third highest run-getter in Test cricket surpassing Rahul Dravid's 13288 runs.
Kallis also spoke of the difficulty and application needed during his innings, which was well-paced under testing circumstances.
"In the situation that we were in it was important to consolidate a bit and make sure we got back on track after losing a few wickets," he said.
"We basically tried to pace the innings and keep the scoreboard ticking. It was quite difficult to score because the wicket was quite slow, they (India) put up defensive fields and bowled quite defensively,” he said.
"As we got closer to their total we could afford to be more positive. I thought the guys really paced the innings well," he signed off, hoping for victory in his farewell Test.
"It is a special feeling," Kallis said.