MANCHESTER - Scott Quigg defended his World Boxing Association super-bantamweight title with a second round stoppage of Argentina's Diego Silva Saturday. He twice floored Silva with a powerful right hand and the beaten challenger was left flat on his back and in need of medical assistance. Quigg had been elevated to the title earlier this year and was, in the opinion of experienced observers, fortunate to hold on to the belt on a draw against Cuba's Yoandris Salinas last month. But Quigg, who comes from Bury near Manchester, did not have to contend with any such doubts after Saturday's decisive victory. "A lot was said after my last fight but I definitely proved tonight that I am world level and now I want to go on and seek out big fights and try to unify the title."–