I dont know what Jannik Sinner has been drinking maybe "Kool Aide" though he thinks he is one of a few players that can defeat Novak on grass?
Well Jannik did take 2 sets off Novak in the QF last year at Wimbledon, though you have to be in top physical condition for starters to go toe to toe with Novak, over 5 sets of tennis, considering the illness and injury woes, so far this year, Jannik recently had to retire in Halle because of a injury., I cannot see him challenging Novak on grass at Wimbledon this year, he is projected to meet Novak in the SFs quite frankly I cannot see that happening.