Wonderful colours! Not much wrong with this photo in my opinion; however, it's kind of a weak shadow. I find the beauty of this photo (the green grass, the clubhead contacting the ball, and Sergio) take away from the shadow.
I think I'd like to see the action frozen more (the sand not blurred like it is) or the whole swing blurred more. It's a pretty nice action shot, though. Good timing!
I see the shadows in this photo, yet they are not adding anything interesting or special to the overall impact of the image... With 'shadows' being the subject of this challenge, I feel that the shadows should be playing some definite role in the image...