David Murdoch's double take-out final stone fired Britain into the men's curling semi-finals, while Elise Christie stormed into the quarter-finals of the short track 1000 metres on day 11 of the Sochi Winter Olympics.

Murdoch's high-pressure stone secured a last-end 6-5 tie-break win over Norway and a semi-final meeting with Sweden on Friday, when Britain's women will also be in last-four action against Canada.

Meanwhile, Christie put her recent troubles behind her with an impressive victory in her 1000m heat, starting cautiously at the back of the field, making her move to lead and then skating away from her rivals.

It was just the confidence booster the 23-year-old Scot needed after a traumatic start to her Games, which saw her disqualified from the 500 metres final, suffer threatening messages on social media and fail to finish her 1500m heat.

Murdoch's all-Scottish curling rink had been beaten by the Norwegians in their round-robin fixture and had to play catch-up for most of Tuesday's game until his brilliant final stone in the 10th end secured two game-winning points.

Murdoch's double take-out match clincher came after a tension-building time-out, where Swedish coach Soren Gran came on to the ice to help the British rink decide whether to go for the shot or hand advantage back to the Norwegians at the extra end.

Murdoch said: ''I stood back and saw there was a shot for two and once we'd seen that, we were always going to go for it.

''Sometimes you just have to go for it. You have to trust everything you have done previously, all your practice shots.

''We had the courage to go for it and were confident we were going to take it. I have played those guys a hundred times and the chances of stealing an extra end is very slim. So, as hard as the shot was, we had to go for it."

Britain will face either China or Canada if they beat the Swedes on Wednesday night - 1900 local time (1500GMT).

Christie, who will now switch her focus to Friday night when she renews her bid for a medal in the 1000m quarter-finals, stressed how the support she has had from people back home brought a smile back to her face when she was at her lowest ebb.

She said: ''Obviously I spent a few days feeling quite down and struggling psychologically. I was then told about all the good support back home and that really boosted me.

"I smiled for the first time in a while when I heard that and I can't get across how thankful I am because I was considering not getting back on, and the support I have had is what has pushed me to get back on and do that.''

Asked if she had seriously considered pulling out, Christie said: ''I did after the 1500. I thought, 'I don't want to do this' but I would never pull out really because I always have that grit in me that keeps me carrying on. But I was feeling pretty low, the lowest I have felt in my career.''

There was mixed fortune for Team GB in the men's 500m heats, with Jon Eley going through to Friday's quarter-finals while Jack Whelbourne missed out.

Eley, the British flagbearer at the opening ceremony in Sochi, was up against home hopeful and 1000m Olympic champion Victor An in heat five but followed the Russian through for second place, clocking 41.554 seconds. Whelbourne, competing in heat four, came home fourth in a time of 42.513secs.

British freestyle skiers Murray Buchan and James Machon failed to qualify for the first ever Winter Olympics halfpipe final in Sochi.

Buchan finished 17th with a top score of 62.40 in difficult conditions at Rosa Khutor Extreme Park, while Machon (52.20) placed 23rd, with only the top 12 qualifying for the final.

''I'm a little bit disappointed,'' Buchan said. ''But I'm absolutely ecstatic I managed to land two runs and get a decent place in."

For Machon, even competing in Sochi represents an extraordinary achievement. The 23-year-old from Sheffield tore an anterior cruciate ligament in his knee last year and although he was a big doubt, he has managed to participate.

''I was out most of last season and it was looking virtually impossible for me to make the Olympics eight months ago,'' he said. ''I worked really hard on my rehab and everything's paid off.''

In the women's bobsleigh at the Sanki Sliding Center, Paula Walker and brake-woman Rebekah Wilson are placed 12th at the halfway stage after their opening two runs.

The pair were slightly disappointed with their runs, of which their second was marginally slower and which leaves them just over a quarter of a second off their stated aim of a top 10 place.

Wilson, who is making her Olympic debut, said: ''The drive went really well - much better than in training. If we could get into the top 10 that would be a good result for us, because it is a really difficult track.''

American pair Elana Meyers and Lauryn Williams will take a healthy 0.23 seconds lead into the final day after setting a track record of 57.26secs on their opening run.