Novak Djokovic negotiated the challenge of Feliciano Lopez in four sets, the top seed into the US Open semi-finals for a ninth consecutive year.

The 2011 champion had played Lopez just once since lifting the silverware in New York, and narrowly avoided being taken the distance in a 6-1 3-6 6-3 7-6 (7-2) triumph on Arthur Ashe Stadium.

Djokovic's victory sets up a blockbuster with defending champion Marin Cilic, the Croatian having never beaten the Serb in 13 career meetings.

The first set was a 25-minute procession, Lopez's fortune summed up when he double-faulted via a net cord to hand Djokovic a double-break lead.

Lopez framed a return of serve to hand Djokovic the opener in limp fashion, but he immediately launched his challenge - the Spaniard affecting the only break of the second set for a 2-0 lead, holding his buffer to square the match.

Serving for the set at 5-3 30-40, Lopez was aggrieved with being denied the chance to challenge an overruled call - but replays showed Djokovic had found the baseline, and the replayed point was won by the left-hander as he went on to hold serve to make it one-set all.

Djokovic repaid the favour with an early break in the third, Lopez blowing game points having gotten out of a 0-40 hole to lose serve regardless.

Lopez served first in the fourth and was the only of the pair to have a sight on a break point, with Djokovic staving off two with some big unreturned serves in the sixth game.

And Djokovic was clinical in the tie-break, taking both points on Lopez's serve to go from 2-1 to 4-1 up and never relinquish the advantage.