I got this one in the nick of time, I couldn't have been anymore closer! But in World Tour on the third race of the first series (the second Sprint race) you have to do 5 laps on a really small course. I was simply just trying to not fall off but when I was on the last lap and saw the guy in last place near I slammed on the boost and overtook him just as we were both touching the finishing line.
So I recommend this course as I was able to do it without really needing to try, if you do tricks to improve on your boost and continue to boost at all times (I didn't) then this achievement should become even easier.
So remember, you have to overtake the guy that's in last place when you are in first, lapping them. Can be done on any lap of the race.