Cilic, ranked 15th, holds an impressive 31-11 match record on the year. His ranking sits at 15 in the world.

Reflecting on the match, Somdev said: 'I let him comeback into the match but credit goes to him for fighting back and giving himself a good chance for a third set.'

Unseeded Australian Lleyton Hewitt, playing his first match since Wimbledon, advanced to the second round with a 7-5, 6-2 win over American wild card Donald Young in a match that featured nine breaks of serve.

Hewitt said that he was happy to make a winning start to his U.S. Open Series campaign at the ATP World Tour 500 hard-court tennis tournament. Hewitt, who is No. 42 in the ATP rankings, has a chance to press his claim for a top-20 spot this summer after missing the entire US hard court swing last year following a hip surgery.

Russian Mikhail Youzhny won on his Washington debut as he defeated American Robert Kendrick 7-5, 3-6, 6-1, while Yen-hsun Lu of Chinese Taipei battled past American wild card Michael Russell 4-6, 6-1, 7-5 to set up a second-round clash with defending champion and No. 2 seed Juan Martin del Potro.

In another first-round match, German Phillip Petzschner rallied past Russia's Teimuraz Gabashvilli 4-6, 6-3, 6-4.