By Chris Oddo

(February 21, 2013) -- 20-year-old American Jack Sock's run at the U.S. National Indoors came to an end last night at the hands of 31-year-old Feliciano Lopez, 6-4, 6-3.

Sock stayed even with the hard-serving Spaniard in the early going, but the crafty lefty managed a break in the seventh game and used it to grab the first set 6-4.

For Sock, who upset 2nd-seeded and two-time Memphis finalist Milos Raonic in the first round and took out James Blake on Thursday, Lopez's tricky array of backhand slice, wicked serves and spontaneous net forays proved to be a bit overwhelming. Experience undoubtedly played a part in Lopez's success, too, as the former World No. 15 found ways to notch the big blows when he needed them. Lopez converted 3 of 8 break point opportunities, and did an excellent job of reading and returning the American's booming serve, particularly in the second set, when he won 13 of 26 points against Sock's first offering and broke the Nebraska native twice.

Sock, who was bidding to reach his first career semifinal, will rise to a projected No. 133 in the rankings despite the loss, a career high.

Lopez's milestone 300th career win earns him a date with Uzbekistan's Denis Istomin in the semifinals. Istomin ensured that no American would reach the final for a second consecutive year in Memphis when he dispatched 34-year-old Michael Russell, 6-4, 7-6(5).

Istomin and Russell traded breaks twice in the first set, before Russell handed the decisive break to the 26-year-old with a double fault. They traded breaks twice again in the second set before heading to a tiebreaker.

In the top half of the draw, Kei Nishikori became the lone seeded player to reach the semifinal when he made short work of top-seeded Marin Cilic, 6-4, 6-2. The fifth-seed will face unseeded Marinko Matosevic of Australia in the semifinals. Matosevic came from behind to upset seventh-seeded Alexandr Dolgopolov, 6-7(6), 6-2, 6-4.

(Photo Credit: AP)