Phillips played 20 minutes for the Ospreys in the victory that took them to the top of the Magners League two weeks ago and then sat on the replacements bench for Wales against France last week.
He is hoping to use the game at Murrayfield to convince Wales coach Warren Gatland he is ready to reclaim his Test spot for the final two rounds of the RBS 6 Nations.
His battle with Blair will be one of the highlights of the weekend in the Magners League as the race for the Play-Off places goes up another level.
Blair has been released by Scottish coach Andy Robinson to bolster Edinburgh's hopes of returning to the top four Play-Off Zone.
Blair was made joint captain of Scotland with his Glasgow Warriors rival Chris Cusiter in the November internationals, but was hampered by injury coming into the RBS 6 Nations.
The first v fifth clash at Murrayfield will also give him a massive opportunity to push for a starting berth against England at the same venue next week and will also give him the chance to have another tilt at Phillips, who beat him to the Lions Test jersey in South Africa last summer.
Another player who will have his eyes on an international return is Ospreys wing Nikki Walker, who has been in the Scottish 6 Nations squad but, as yet, not been required for duty.
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