Sochi 2014: GB seventh at halfway in men's four-man bobsleigh

Great Britain are seventh and in contention for a medal halfway through a four-man bobsleigh competition that Russia lead.

Russian pilot Alexander Zubkov, 39, who won two-man gold last week, holds a 0.04-second lead over Latvia in second.

GBR 1, driven by John Jackson, finished their first two runs in a combined time of one minute 50.53 seconds, 0.18 secs off Germany in third.

Lamin Deen's GBR 2 team are joint 18th before the final two runs on Sunday.

Starting positions were based on world rankings, meaning Jackson's team began in 12th position, something the pilot saw as a distinct disadvantage. However, he was pleased with how the crew responded.

"We've seen it in training all week - the first three sleds go down on the ice really quickly, but then it's damaged and everyone else is struggling to match those times," he said.

"We had a good second run today and hopefully that'll put us in a strong position tomorrow to be on better ice and move up the order a bit."

Great Britain have been set the target of a top-six finish at the Winter Olympics by UK Sport.

After the GB women failed to achieve their target of a top-eight result - coming 12th - there is pressure to produce a result that will secure the sport financing through to the 2018 Games in South Korea.

"Bobsleigh is moving on all the time and to keep up with that we need to keep developing, and that takes funding," Jackson told BBC Sport.

The Canada 3 team suffered a heavy crash that delayed the second run

"We have made massive strides but we will drop back if that support doesn't continue."

GB performance director Gary Anderson added: "Our aim was to go into the second day with the leading group.

"Our start position of 12th in the first heat was always going to be tough, but our second run has put us back in the hunt and we will give everything tomorrow to move up the leaderboard."

While Jackson made an encouraging start, Deen endured a frustrating day.

Andy Matthews only joined the four-man team last week as a late replacement for injured Beijing Olympic sprinter Craig Pickering and the GBR 2 pilot admitted that had had an impact on his crew.

"Andy's come in and done really well, but he's 10kg lighter than Craig, so we've had to load the sled [with weight] and that has an impact on how the sled drives," he said.

The Canadian number three team suffered a dramatic crash on their second run, which pilot Justin Kripps blamed on his national federation.

They switched his three 'pushers' with those from the Canadian number one team on the eve of the competition in a bid to boost his prospects.

The penultimate third run will begin at 09:30 GMT on Sunday, with the final run scheduled for 11:00.