SAN FRANCISCO » Second-half substitutes Mix Diskerud and Aron Johannsson scored to lift a heavy legged United States over Azerbaijan 2-0 on Tuesday night in the first of three World Cup warmups for the Americans.

On a night when captain Clint Dempsey was scratched just before kickoff because of a sore left groin, the 14th-ranked Americans had trouble breaking down No. 85 Azerbaijan.

Diskerud, a Norwegian-American midfielder entered in the 71st and scored four minutes later off Brad Davis’ free kick.

With the ball high in the box, Diskerud headed it down to Michael Bradley, whose shot was cleared off the goal line by Elvin Yunuszade. Diskerud then banged the ball in from 6 yards for his third international goal.

He was wearing the No. 10 jersey that freed up when Landon Donovan was cut from the roster last week.

"For me, it’s just a number," Diskerud said. "I feel like I’m just borrowing it. We’ll play together someday, and he’ll get it back."

Johannsson, an Icelandic-American, entered in the 62nd and scored his second American goal in the 81st with an open header from the top of the 6-yard box off a corner kick by Davis, who replaced Graham Zusi at the start of the second half.

Tim Howard, making his 98th international appearance, got his 53rd win to tie Kasey Keller’s U.S. record. The Americans began their intense two-week training camp May 14 at nearby Stanford University, and there appeared to be tired legs.

"I think we can be very happy with this game," Johannsson said. "We’ve been working ridiculously hard in training."

Next up is a match Sunday against Turkey at Harrison, N.J., followed by a game with Nigeria six days later in Jacksonville, Fla. Then the Americans head to Brazil for their seventh straight World Cup appearance and first-round matches against Ghana, Portugal and Germany.

"It was exactly what we need at this point of our preparation after two fully loaded weeks," U.S. coach Jurgen Klinsmann said.