Marin Cilic's US Open title defence remains alive as he reached the semi-finals with a five-set win over Jo-Wilfried Tsonga on Tuesday.

The Croatian ninth seed secured a 6-4 6-4 3-6 6-7 (3-7) 6-4 win over Frenchman Tsonga to advance to the last four at Flushing Meadows for just the second time.

Cilic needed five match points, including squandering three in the fourth set, to finally advance to a meeting with either Novak Djokovic or Feliciano Lopez.

On the back of a fine serving display – Cilic served 29 aces – and 63 winners, Cilic sealed a 12th straight win at the US Open.

Tsonga battled a knee injury throughout before lifting in the third and fourth sets, only to give up the only break in the fifth.

Cilic appeared to be moving gingerly on a heavily strapped ankle in the early stages and he had to gather himself after a slight wobble allowed Tsonga four break points at 2-3.

Tsonga had been let off the hook a couple of times with ill-judged slicing, but the Frenchman was struggling to land enough serves and Cilic made the only break of the set in the ninth game - the first time Tsonga had dropped serve all tournament.

Having lost the opener, Tsonga seemed dispirited and was struggling on some longer service games and a double fault in game five gifted Cilic a set and break lead.

There was a brief moment of worry for Cilic in the next game as Tsonga got to 0-30 after a one-handed cross-court backhand, but the Croat recovered and the rest of the set raced by.

Tsonga had his left knee taped after lengthy discussions with his trainer, and the 19th seed appeared reinvigorated in the third set - ensuring he stayed ahead on the scoreboard.

And he roared back into the match by breaking in game eight when Cilic failed to return a backhand, before Tsonga served out with a huge ace.

Tsonga saved two match points in the 10th game and another in the 12th, the third after Cilic put a tame slice into the net.

At 2-2 in the tie-break, Cilic served a double fault, having avoided one by the smallest of margins a point earlier and via a challenge and Tsonga would run away with the tie-break regardless as he levelled the match.

Both players had their chances early in the fifth, but it was Cilic who broke for 3-2 before seeing out his win.