It was 24-year-old Kenny who was sitting pretty atop the standings in the Netherlands after the first two days of competition.
But all that changed after the third evening of competition and it is Hoy who is the man to beat now as he put on a masterclass on Saturday.
Hoy and Kenny had teamed up on the opening two days of competition to win the team sprint, but Britian's most successful Olympian of all time was paired with Dutchman Teun Mulder on Saturday.
And Hoy put friendship behind as he and Mulder beat Kenny and Gregory Bauge, before returning to the track in the individual sprint to pip Kenny again in the final.
However in the keirin the British dominance was final ended as Mulder claimed victory, Hoy and Kenny having to settle for second and third respectively.
These results mean Hoy is two points ahead of Kenny at the halfway stage, with Mulder third and Bauge fourth.