The Six Nations returns this week to begin its rapid run towards a climax, with the contest for British and Irish Lions tour places sure to provide plenty of compelling sub-plots.

In just over a month's time, Lions coach Warren Gatland will announce a squad that he hopes will feature the very best players from England, Scotland, Ireland and Wales for the three-Test series against his native New Zealand in June and July.

Of the three countries the Lions tour every four years (South Africa and Australia are the others), it is New Zealand that is considered the acid test for the combined side.

They have won just one series in New Zealand, in 1971, and the fact that the victorious players from that campaign -- JPR Williams, Gerald Davies, Mike Gibson, Barry John, Gareth Edwards, Willie John McBride and Ian McLauchlan to name a few -- are still revered more than 45 years later shows that sporting immortality lies in wait for this year's Lions if they can upset the odds and beat the reigning world champions.

The final two weeks of the Six Nations represent the final proving ground for Lions hopefuls and the tournament offers Gatland the chance to witness a number of head-to-head contests between potential tour rivals.

Perhaps the most eye-catching duel in the opening fourth-round match in Cardiff on Friday will involve Wales's Rhys Webb and Ireland's Conor Murray, widely regarded as the two best scrum-halves currently available to Gatland.

Murray, 27, already knows what it is to be a Lion, having featured in the succesful 2013 series in Australia alongside Ireland half-back partner Jonathan Sexton, also tipped to feature against the All Blacks.

The half-back pair know what it means to beat New Zealand, having been involved when Ireland ended their 111-year wait for a maiden win over the All Blacks with a 40-29 success in Chicago in November.

And yet the fit-again Webb has clearly added a new snap to Wales's back division and was arguably their best player in a 29-13 loss to Scotland at Murrayfield.

Just as British politicians who want to become Prime Minister routinely disclaim all interest in the job until the last practical moment, so too do Lions candidates say they their focus is solely on the next game rather than selection for the multi-national side.

Certainly if Webb delivers an on-field performance to equal his pre-match comments, it will be a masterclass.

- 'Focus' -

 "I am not one to get to caught up in individual battles," Webb said. 

"He (Murray) and Sexton are a big part of the Irish team. They have a good kicking game which we have to be aware of and apply lots of pressure to them.

"There will be a lot of focus on the nine (scrum-half) battle, but that is for you (media) and spectators."

England, looking to equal New Zealand's record of 18 successive Test wins by defeating old rivals Scotland at Twickenham on Saturday, are sure to boast a strong Lions contingent of their own.

But it says much about Scotland's revival under Kiwi coach Vern Cotter, which includes wins over Ireland and Wales already this Six Nations, that both fullback Stuart Hogg and lock Jonny Gray are widely tipped for Lions' selection -- and not just to make up the numbers.

Scotland, for all their recent progress however, have not won at Twickenham since 1983.

As for the tournament itself, if Wales beat Ireland and England see off Scotland, then defending champions England will have all but retained their title, although bonus point considerations, a new factor this season, could yet delay a trophy presentation until the tournament finale on March 18.

This week's other Six Nations match sees Italy at home to France on Saturday, with both the Azzurri and Les Bleus looking to bounce back from defeats by England and Ireland respectively.

Source: AFP