A fourth break point is squandered by Steve Darcis.

Great Britain treading water rather than swimming for the finishline at the moment.

Darcis with another break point. And a Jamie Murray second serve to look at. He wallops into the net as Andy Murray creeps across the front of the net to put him on return.

Here comes a sixth (!) break point of the game though...and a Jamie Murray kick serve is good enough to scrape it back off the table.

Number seven coming up...

Great Britain repair some of the damage, Jamie Murray slam-dunking away an overhead to make it back to the sanctuary of deuce from 0-40 down.

Don't start reading the last rites on David Goffin and Steve Darcis just yet.

Darcis whips a backhand return away for 0-30 in response to the Jamie Murray serve.

Another sublime angle from Darcis - who has surely played his way into tomorrow's singles - brings up 0-40 and three break points.

When the going gets tough, the fans get going...

Image source, AFP

Andy Murray is all over the front of the court like an outbreak of head lice in nursery.

The world number two hammers away the killer volley after a Steve Darcis double-fault had handed GB a break point on a platter.

Andy and Jamie Murray are turning the screws now. A backhand from Andy that perfectly bisects the Belgians brings up deuce.

No-one like bisected Belgians.

Andrew Castle
BBC Sport tennis commentator

Andy Murray's block-buster serve is a weapon that no-one else on court has.

It is a bazooka at a knife fight.

Steve Darcis can only pat his return wide on the final point.

Image source, Reuters

A deliriously good point to start Andy Murray's service game - back and forth they whack and wheedle before David Goffin plugs away a backhand to finally take it.

Goffin slides away an angle on volley for 0-30 - six points in a row for the Belgians at the start of the set.

Brilliant reflex volley from Jamie followed by a delicious top-spinning lob from Andy stops the rot.

A ram-jamming serve brings up 40-30, but Steve Darcis dismissively dusts a backhand across court to bring up deuce.

David Goffin breezes through the first game of the fourth set to love.

A bit of a hold up before the start of the fourth set as the Belgian boys head off for a bathroom break and the umpire descends from the crow's nest to deal with some sort of issue courtside.

All sorted. We are back ready. David Goffin to serve...

Image source, Reuters

Steve Darcis cracks into the top of the net as he tries to ping a forehand into the nether regions of the Murray brothers and end Judy's chances of grandkids. That is 40-15 and two set points.

The second is the keeper for Great Britain as a pacy Andy tee-off is too hot for Darcis to handle.

The hipster John Bull figure in the crowd - blue bushy beard and union jack sunnies to accompany his braces and sharp slacks - enjoyed that.

Tom Gumbleton: I can't take this drama and sense of historic occasion in the #DavisCupFinal, external my heart is beating too fast.

It has been Breaksville, Tennessee so far in this set.

Jamie Murray hammers away on the backhand, hard into the red dirt to bring up 0-40.

David Goffin's wrist crumples under the sting of the British groundstrokes on the next point.

Can Andy Murray break the trend, hold serve and close out this strange old third set?

Image source, AP

Adam Pake: Seriously now, how are they doing it? Darcis is 502 in doubles and Goffin has barely played doubles in his life!

Andrew Bak: Jamie Murray's really been struggling these last two sets. He needs to up his game otherwise we'll lose.

If Jamie Murray can hold here, then Andy Murray will have the chance to serve for the set at worse for Britain.

Jamie's is the weaker tee-off though and a Darcis forehand down the middle exposes too much space between the Murray clan.

Andy Murray into the net - two break points.

And David Goffin hustles Britain out of the first...

Great Britain are on rise.

Andy Murray's volley drops door-nail dead for 30-30.

And then confusion and controversy.

A ball on the Belgian baseline takes half the line, but the line judge call it in...and then out. The umpire out of the chair, Leon Smith rolling his eyes.

It's a let.

No matter, Steve Darcis cannot keep the lid on a volley. Long it flies for 30-40 and break point.

Jamie steps in and volleys away for a winner!

Annabel Croft
Former British number one on Radio 5 live sports extra

John Lloyd
Former Davis Cup finalist on BBC One