Novak Djokovic: 'It was anybody's game in fourth set against Feliciano Lopez'

World number one Novak Djokovic has claimed that the result of his quarter-final match against Feliciano Lopez could have gone either way in the fourth set.

The Serbian eased to a one-set lead at Flushing Meadows in New York, but after dropping serve early in the second, Lopez was able to draw level.

After Djokovic regained the lead at the Arthur Ashe Stadium, it was tough to call in the fourth set as neither player could break serve, and a tie-break was required to separate the pair.

Eventually, the nine-time Grand Slam champion booked his place in the semi-finals in New York with a 6-1 3-6 6-3 7-6(2) victory.

"I played a pretty bad game in the second and the set was gone," Djokovic said on court after the match. "It was anybody's game in the fourth set - he had a couple of break points. I didn't have any chance on his service game and in the tie-break, it went my way. I played pretty good, very consistent, so I'm just glad to get through in four."

The 28-year-old, who won the US Open in 2011, will face defending champion Marin Cilic in the semi-finals.