Head coach Ian McGeechan will closely monitor form in the Six Nations
The Six Nations will be the last major shop window for the cream of Britain and Ireland's rugby talent to stake a claim for a place on this summer's Lions tour to South Africa.
Coach Ian McGeechan will whittle down the prospective candidates as the tournament unfolds over the next six weeks before finalising his 35-man squad in April.
"Individually and collectively there is an incentive to do well in the Six Nations because of what is going on in the summer," admits Ireland skipper Brian O'Driscoll, who led the Lions on their last southern hemisphere venture to New Zealand in 2005.
"The team that does best in the Six Nations will probably have the biggest share of Lions players because they have been the ones in form. So it is a good incentive as a team."
We asked four of the BBC's analysts - former Wales fly-half Jonathan Davies, ex-England centre Jeremy Guscott, former Scotland scrum-half Andy Nicol and ex-Ireland hooker Keith Wood - to choose their own Lions Test team before a ball is kicked or passed this weekend.
Their selections at this stage are represented in the graphic below.
You can also have a go at choosing your own team to take on the Springboks by following this link to our Lions squad selector.
After the conclusion of the Championship with three matches on Saturday, 21 March, our four pundits will revisit their selections to see what difference form over the tournament has made.
In the meantime, we will be undertaking a "Lions Watch" after each of the five rounds of fixtures to assess which players have boosted, or harmed, their prospects of selection.
Let the battle for those hallowed red jerseys commence.