If Scotland are to keep their dream of a first-ever Six Nations title alive going into the final weekend, they must win in Rome and hope for a favour from a beleaguered England in round four of the Guinness Six Nations on Saturday.

Even then, it may not be enough to keep Gregor Townsend’s side in the running for a first title since the final Five Nations quarter of a century ago.

Scotland go into round four in second place with nine points from their three games so far, but six points adrift of leaders Ireland.

Andy Farrell’s side, currently on 15 points, could wrap up back-to-back titles with a bonus point win at Twickenham in the match that immediately follows Scotland’s on Saturday evening.

That would move the Irish onto 20 points, with Scotland unable to catch them even if Townsend’s charges register four tries and a victory in the Italian capital.

READ MORE: Italy vs Scotland: The key battles and important stats ahead of Rome battle

What if Ireland don’t get a bonus point? It’s still a tall order for Scotland.

Ireland would move to 19 points, and Scotland would then require a bonus point win over Ireland in Dublin – and to stop the hosts picking up any match points (a try bonus or a losing bonus) to be in with a shot at the title.

Another stumbling block. If the two sides were tied on points, the championship would be decided on points difference. Scotland’s points difference after three matches is +6. Ireland’s is +81.

However, victory over Italy on Saturday – regardless of how many points Scotland pick up – would set up a Triple Crown decider; a trophy Scotland haven’t won since the Grand Slam year of 1990.

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But it’s all there for Ireland, who know a repeat of their 32-15 win at Twickenham two years ago would see them become the first side in the Six Nations era to achieve the feat of back-to-back Grand Slams.

Elsewhere this weekend, Italy would move off the bottom of the table if they better Wales’ result. The two sides – who meet in Cardiff in round three - are currently tied on three points after the Azzurri’s draw with France in round three.

It has been a difficult campaign so far for France, in fourth on six points currently. Fabien Galthie’s side could move as high as second if they beat Warren Gatland’s side in Cardiff, depending on other results going in their favour.