Phillips, who was a star of last season's tournament, has made an impressive return to form after a lengthy injury absence, while Blair was among the nominees for the 2008 IRB Player of the Year Award.
Both players head into the competition with growing reputations and both are keen to enhance their prospects of becoming a Lion in four months time.
"I'll be trying to do my job as well as I can," said Phillips, who spent nine months on the sidelines after suffering a serious knee injury during the Ospreys' EDF Energy Cup semi-final win over Saracens in the spring of last year.
"I'm aware it is a chance to show who's best. And we all know what is at the end of the season.
"It is vitally important I concentrate on my job with Wales, perform well and then I could be in with a shout (of making the Lions squad)."
Blair explains that performing well on the international stage may be the only thing on his mind right now, but the Edinburgh and Scotland skipper admits that a strong Six Nations could be the springboard to higher honours. The path to those honours starts with today's battle with one of his most-talked about rivals.
"I've not given the Lions much thought," said Blair. "All I want to do is a good job for my country, lead and play well, make decisions to benefit the team that will go a long way to further achievements.
"In every game you want to beat your opposite man, that's something that keeps me going.
"Mike is a very good ball-carrier, makes a lot of breaks and he has a bit of subtlety about his game. And he has returned to form very quickly after his injury."