the 5th at Merion with the back pin position. If playing from the back tees, the approach shot to a tournament/championship speed green can be extremely challenging
the 4th at Sawgrass. you always have to be careful with the drive not reaching the semi rough short of the ditch but if laying up too short, it will leave a long iron shot that is very difficult to a pin often protected by a bunker
the 18th at Merion with the right hand side pin position. It's a tough hole anyway but with that right pin, it's almost impossible to attack with yet another bunker waiting for any under hit irons