"We definitely saw the potential (in 2011) but there is a lot of potential in India and across the world. Like Kohli, many other cricketers had the potential but it's just amazing to watch how he has translated his potential to effectively being the number one batsman in the world," Upton said.
Upton also weighed in on the much-talked about debate as to who would bat at the number four spot for India in the upcoming World Cup beginning May 30 in England and Wales.
According to Upton, anyone could bat at number four, be it Dhoni or Vijay Shankar or KL Rahul, depending upon the situation of the game.
"For me the debate is not more about the number four position but whom do you want to bat at what situation or stage of the game," he said.
"We in cricket are still caught up with numbers as to I will bat at no.3 or 4 whereas its more about understanding who needs to be batting against what bowlers in what situation of the game," he added.
Earlier, India head coach Ravi Shastri had also said the team has got enough ammunition and anyone could bat at the number four position.
The 50-year-old Upton also pointed out that both M.S. Dhoni and Kohli have different approach to bating and pacing the innings when it comes to chasing.
"Well in terms of mental approach to batting, one of the similarities is that both of them stay very focused on their job at hand. They understand exactly how to pace the innings to get to the point where they can take the team across the line. Both of them have very different ways of pacing the innings. Kohli gets to the run rate (required) and literally stays at the run rate from over number one and he accelerates whenever he feels the time is behind," said the South African.
"Dhoni, on the other hand, starts slowly and times the acceleration perfectly. Both of them are equally effective in seeing the team to victory in their unique style," he added.
India will begin their World Cup campaign against South Africa on June 5.
(Aakash Kumar can be contacted at aakash.k@.in)