Dustin Johnson wins WGC Bridgestone Invitational after Jason Day crumbles

Dustin Johnson has taken home the WGC Bridgestone Invitational trophy after carding a four-under-par 66 in the final round in Ohio on Sunday.

The 32-year-old, who won the US Open last month, finished the tournament with a one-shot advantage over his fellow American Scott Piercy.

World number one Jason Day was a strong contender to seal victory as he headed into the final round with a tie of the lead alongside Piercy, but the Australian's campaign collapsed.

Day dropped to three shots off the overall lead after suffering bogeys on the 15th and 18th holes and a double bogey on the 16th.

Two-time Major winner Jordan Spieth finished tied fourth after carding a three-under-par 67 round.