Johnson, Castro three strokes ahead

Dustin Johnson and Roberto Castro claimed a three-shot lead at the BMW Championship on Friday. 

Johnson, the reigning U.S. Open champion, carded a Crooked Stick Golf Club course record nine-under-par 63, while overnight leader Castro fired a seven-under-par 65 for the second consecutive round. 

Johnson and Castro are currently on 14-under, while Paul Casey, who is their closest competitor, is on 11-under. 

Meanwhile, world number one and defending champion Jason Day surged up the leaderboard, but still remains 10 strokes adrift of the lead in a tie for 19th. 

Johnson kicked off his round with two birdie on his first three holes and he went on to complete his round with a 45-foot chip-in eagle from the green side bunker at the par-five ninth. The world number two continued to impress on the back nine as he made three birdies in the space of four holes before concluding his round with a 25-foot eagle putt at the par-five 15th. 

Castro was in sensational form early on as he made five birdies on the front nine, which included a 30-foot putt at the sixth. While he was only able to follow up with two birdies on the back nine, it was still enough to keep him in a share of the lead heading into the weekend. 

Casey, who recorded a 66, made six birdies during his bogey-free round, which included a 23-foot putt at the seventh. 

After registering a 73 on Thursday, Day rebounded with a 67, which began with him making a trio of birdies on the front nine, which included a 20-foot putt at the sixth. The Australian followed that up with another birdie at the 11th before making an eagle at the 15th. Day finished off his round with a bogey at the 16th and has a mountain to climb to catch up with the leaders on the weekend.