Sixth-seeded Kei Nishikori of Japan outlasted world No.2 Andy Murray in the US Open quarter-finals, 1-6, 6-4, 4-6, 6-1, 7-5, on Wednesday."I had many up and downs, in the beginning I didn't start well. It was tough but in the end it was great tennis, so very happy," Xinhua news agency quoted Nishikori as saying.The match lasted three hours and 57 minutes and went for five sets. The fifth and final set started with three straight breaks of serve. Tied at 5-5 with Murray serving, Nishikori scored another break and then served out the match in the 12th game.Last time Nishikori reached the semi-finals was 2014, when he finally reached his first Grand Slam final before losing to Croatian Marin Cilic."I definitely have great memories here," Nishikori added. "Two years ago, I made the final for the first time in the Grand Slams. This is a great opportunity for me, to come in the semi-final here again. This is one of my favourite Grand Slams."