Britain's Andy Murray reacts after winning against Japan's Kei Nishikori during their round robin stage men's singles match on day four of the ATP World Tour Finals tennis tournament in London. Pic/AFP

London: Andy Murray got revenge on Kei Nishikori for his defeat at the US Open but needed to battle for more than three hours to do so, gutting out a 6-7 (9-11), 6-4, 6-4 victory here in Group John McEnroe action at the ATP World Tour Finals.