Team GB have guaranteed their first medal of the Winter Olympics after the men's curlers defeated USA 8-4 to book their place in the gold medal final.
Bruce Mouat's men battled back from a nightmare start and held their nerve over the closing stretch to beat the Americans 8-4 and secure a Saturday showdown against reigning world champions Sweden.
Team USA stole two in the second when Mouat was unable to get behind a three-stone block with the final throw end, only for Mouat to take advantage of John Shuster's misjudged final throw in the third to use the hammer and take three for Team GB.
Shuster responded with a magnificent shot at the end of the fourth to pick up two and give America a slender lead, before Mouat nudged Shuster out of the house with the final stone of the fifth end to move Team GB into a 5-4 halfway advantage.
The two teams couldn't be separated over the next three ends, exchanging three blanks, before Team GB grabbed a steal in the ninth and picked up two in the final end - when Shuster's final attempted take-out went awry - to knock out the defending champions.
Team GB will return to the ice at 0605 GMT on Saturday to play Sweden, who defeated Canada in another close semi-final. Team USA and Canada will compete in the bronze medal contest on Friday morning.
Team GB through to women's semi-finals
Great Britain women squeezed through to the semi-finals after Eve Muirhead helped to fashion a great escape and keep their unlikely medal hopes alive.
Team GB went into the last match of the round-robin phase against the Russian Olympic Committee requiring at least three results to go her way in order to book a top-four spot.
Muirhead kept her side of the bargain with a brilliant double take-out in the penultimate end to score four and sink the Russians 9-4, then waited nervously while Sweden beat South Korea in order to guarantee their place.
Locked together with two other teams on a 5-4 win-loss record, Muirhead's team advanced by virtue of the 'draw shot challenge' system - an average of the accuracy of the final pre-match draw shots played prior to every round-robin match.
It placed Team GB in third place, ahead of Japan and Canada, with the latter being eliminated. Muirhead's team will face second-placed Sweden in the semi-finals, with Japan taking on Switzerland for a place in the gold medal match.
"We had to win that game today and that was the first thing we went out there to do," Muirhead told BBC Sport. "We fought our hearts out, nothing was in our control apart from our own game. Of course, we maybe had one eye on the other games, but I see we managed to get a semi-final spot from a centimetre on the draw shot."
Both semi-finals take place at 1205 GMT from Friday, with the gold medal match at 0105 on Sunday. The bronze medal match, played between the two losing semi-finalists, will be played at 12:05pm on Saturday.