John Simpson won the WBO international title with a points victory over veteran Mongolian Choi in Glasgow on Saturday night.
In a fight that whetted the appetite ahead of Ricky Burns' victory over Jose Gonzalez, Simpson gradually asserted against the 41-year-old 'Iron Monk'.
Simpson went in with 25-9 record but clearly has plenty to offer yet after successfully making the transition to super-featherweight.
As expected, Choi came out strongly and the Scot had to weather the early storm, reeling from fierce body shots as the veteran went for a swift stoppage.
Simpson foolishly waged war in the second round but quickly learned his lesson and started to have more success as he stuck to his boxing skills on the outside.
His longer reach was working well and although Choi continued to have his successes, particularly downstairs, Simpson looked increasingly confident the longer the fight went on.
Heading into the final round it appeared either could still take it but Simpson stayed out of trouble, seemingly aware he had already done enough.
In the end the scores of 116-112 117-112 116-113 flattered the Scot, although the result was the correct one.