While one was arguably the greatest stage racer of his generation, the other was arguably the greatest Classics rider, yet there's more than a little crossover between the two, and we put your knowledge to the test in our latest Cyclingnews quiz.
Tom Boonen turned professional in 2002, Contador a year later. Both enjoyed long and successful careers, though both were tarnished by doping cases. Contador having served a ban and been stripped of two Grand Tour titles for a Clenbuterol positive, Boonen having been barred from the 2009 Tour de France for cocaine use.
Both, however, went on to establish themselves as fan favourites. Boonen was the Belgian media darling, the star whose fame transcended his sport, while Contador secured a reputation as one of the most exciting riders to watch, someone who wasn't afraid to risk everything to light up the race.
But who won more and how do their palmares compare?
Tour de France stages, national titles, World Championships medals... It's all up for grabs in our latest quiz.
For each question we select an event and you have to tell us whether Boonen won more, whether Contador won more, or whether they were equal.
Enjoy the quiz and let us know how you get on in the comments section below.