That's a terrific photo, I'd love to have witnessed that and photographed it. The sparrowhawk is almost certain to win. I was cycling home along a country lane once and heard this terrific ruckus in front. As I came around a slight bend there was a stoat rolling around in the road with a rabbit squealing like mad. To add to the confusion there was a cock blackbird flapping around, dive-bombing the stoat and making loud warning calls. After several minutes the stoat backed off and the rabbit lit off up the road at a rate of knots, and the blackbird dove onto the stoat a couple more times until it vanished into the hedge. Amazing sight, glad I witnessed it.