By Steve Keating
NEW YORK (Reuters) - Marin Cilic kept his U.S. Open title defense on track but not without a scare as the ninth seed needed over four hours to put away Mikhail Kukushkin and reach the fourth round with a 6-7(5) 7-6(1) 6-3 6-7(3) 6-1 win on Friday.
Cilic stepped onto the Grandstand court having won 16 straight sets at Flushing Meadows but that string quickly came to an end when the 56th-ranked Kukushkin took the opening set in a tiebreak in what was the start of a long and harrowing afternoon for the defending champion.
After crashing out in the first or second round of his last 16 tournaments, Kukushkin appeared determined to maintain an extended grand slam run following a second-round upset of 17th seed Grigor Dimitrov.
For four sets, the 27-year-old from Kazakhstan gave Cilic all he could handle and more but in the fifth he simply ran out of steam as the Croat surged ahead 5-0 before closing out the marathon encounter with his 27th ace.
(Editing by Mark Lamport-Stokes)