* Unlucky 13 for U.S. as Costa Rica end streak
* Early goals set stage for victory (Adds quotes)
Sept 6 (Reuters) - The United States' 12-game winning run came to a crushing end with a 3-1 defeat against Costa Rica in their CONCACAF region World Cup qualifier in San Jose on Friday.
Two early goals for a fired-up Costa Rica set the tone for a tough encounter and although the Americans sit in second place in the six-team qualifying group behind the hosts, the result will be of concern to head coach Juergen Klinsmann.
"We knew they were going to come out that way and we gave away a careless corner and they scored from it," midfielder Landon Donovan told reporters.
"We have got to do better. Now we go home and we have a must-win game against Mexico on Tuesday," he added.
The U.S. suffered a blow shortly before the game when key midfielder Michael Bradley limped off the field with an ankle injury during the warmup and Geoff Cameron had to be thrust into the starting side.
Costa Rica surged out of the blocks and grabbed the lead in the third minute when Jhonny Acosta headed in a corner at the near post past DaMarcus Beasley on the line.
Seven minutes later it was 2-0, when Cristian Bolanos floated a ball towards the back post and Celso Borges rose superbly above Beasley to head home.
The game should have been put beyond the Americans in the 24th minute when Brian Ruiz set up Bolanos but the midfielder hesitated and his shot was deflected wide.
Costa Rica keeper Keilor Navas was brought into action in the 29th minute when he pulled off a great save to keep out a fierce drive from Fabian Johnson.
At the other end, U.S. keeper Tim Howard was out quickly at the feet of the livewire Joel Campbell but the Americans got a lifeline two minutes before the interval.
Johnson was brought down inside the area by Navas, who had charged off his line, and Clint Dempsey marked his 100th international appearance with a successful penalty kick to get the Americans back into the contest.
Klinsmann's men started the second half well with Donovan finding Dempsey, who wriggled onto his left foot and fired a left-foot shot against the post.
But Campbell made sure of the three points for Costa Rica, racing on to a long ball, outpacing Matt Besler and slipping the ball between Howard's legs.
A bad night for the Americans was made worse by yellow cards for Cameron, Besler and substitute Jozy Altidore - all of whom will now miss Tuesday's clash with Mexico in Columbus.
Klinsmann will now have to bring in some back-up players for Tuesday's game and said he would make a quick decision.
"Obviously with the yellow cards we are going to sit down now and discuss all the elements that we want to change for Tuesday," the German said.
"We knew about the risk, the situation, but it is always upsetting when it happens, especially when you look at Jozy Altidore, whose yellow card at the end was absolutely unnecessary."
Altidore, who came on as a substitute, was booked for a petulant push in injury time.
After seven rounds of matches, Costa Rica lead the way on 14 points with the United States on 13 and Honduras on 10, while Mexico sit in fourth place, outside the automatic qualification slots, on eight points in the final stage group.
Panama are on seven and Jamaica are bottom of the standings on three points. (Reporting By Simon Evans; Editing by Ian Ransom/John O'Brien)