Tennis: Serena into semis despite early Pironkova scare

Serena Williams is through to the semi-finals of the US Open after overcoming an early scare against Tsvetana Pironkova. The third seed came from a set and a break down to overcome the Bulgarian 4-6 6-3 6-2. The 23-time major winner will face either Elise Mertens or Victoria Azarenka in the last-four.