A masterstroke from skipper Rhona Martin helped Britain's curlers to a 5-4 victory over Switzerland - the team they beat for gold in 2002.
Skipper Martin consistently outplayed her Swiss rival
It was a tight contest throughout and the teams were locked at 4-4 going into the last end of Tuesday's contest.
The Swiss had the crucial last "hammer" stone, but superb play by Martin forced an error from rival skipper Mirjam Ott.
Britain have now won both their matches in the round-robin, following Monday's 3-2 victory over Denmark.
The Swiss were favourites to make the final four, having taken the silver medal at last year's European Championships, and Martin was delighted with the win.
"We just kept plugging away and trying to be patient, but it was hard not to be frustrated when we knew she had the hammer at the last end," she said.
"We stepped up a gear today and we are getting to know ourselves better as a team now. But we still have a long way to go and a lot of sharpening up to do."
Head coach Mike Hay said the women were now in a great position in the competition.
"We are not being complacent because there are a lot of good teams out there, but it is definitely where we want to be," he said.
"Going into the 10th end with the ice fairly straight you don't really expect to win, but Rhona took full advantage of an unexpected miss by their third.
"We lost momentum midway through the game and the Swiss played well but we showed character to take it on the chin and that was important for us."