Watch: Day aces par-3 17th at BMW Championship

The caddie switch is definitely paying off for Jason Day this week at the BMW Championship.

Day was 4-under par on his round Friday - and 11-under par for the tournament - when he arrived at the par-3 17th. Then, the Aussie got a great bounce on the 188-yard hole as his 7-iron landed just short of the green and rolled into the cup for his second career hole-in-one on Tour.