|RBS Six Nations: Scotland v Wales|
|Venue: Murrayfield, Edinburgh Date: Sunday, 15 February Kick-off: 15:00 GMT Coverage: Live on BBC TV, HD, Red Button, Radio 5 live, BBC Radio Wales, Radio Cymru, the BBC Sport website, BBC iPlayer, S4C online, mobile, the BBC Sport app and Connected TV; text commentary on the BBC Sport website.|
Wales fly-half Dan Biggar says their 2015 Six Nations title hopes will end if they lose against Scotland on Sunday.
Wales lost their opening match 21-16 at home to England, despite leading 16-8 at half-time.
Scotland also lost their opener 15-8 away to France in Paris and Biggar expects a "tough" match at Murrayfield.
"I think the team that loses, the Six Nations is gone for them, so it's a must win game," said Biggar.
Wales have not lost to Scotland since 2007 and, after full-back Stuart Hogg was sent off in the 22nd minute of their final 2014 tournament game, Gatland's side hammered them 51-3 in Cardiff.
That gave Wales a record seventh consecutive win against the nation now coached by New Zealander Vern Cotter.
|Wales in the 2015 Six Nations|
|Friday, 6 February: Wales 16-21 England|
|Sunday, 15 February: v Scotland, Murrayfield|
|Saturday, 28 February: v France, Paris|
|Saturday, 14 March: v Ireland, Cardiff|
|Saturday, 21 March :v Italy, Rome|
Despite the impressive head-to-head record against the Scots, Biggar is not expecting an easy time in Edinburgh.
"We're expecting a very tough match," said the Ospreys number 10.
"I thought they were excellent against France and were very unlucky not to have won that game.
"Yes, our record against them is good, but we are probably going to have to be a little bit better than we were on Friday to pick up a result.
"It's going to be a huge, huge Test match. It's something that both teams need to win."