CONOR MURRAY v KAHN FOTUALI'I
Ireland's physical half-back Murray's rapid elevation was underlined by his British Lion status in the summer's victorious Australia tour.
Munster man Murray took on Samoa's Northampton scrum-half Fotuali'i during that tour, when the Lions overwhelmed the Barbarians 59-8 in Hong Kong.
Former Ospreys nine Fotuali'i claimed the Barbarians' only try in that clash though, and is widely regarded as one of the world's best scrum-halves.
The Samoan general can run a game on his own if allowed, so Murray will have to impose his authority from the off. Whoever takes control here could direct the game.
BRIAN O'DRISCOLL v GEORGE PISI
Elder statesman centre O'Driscoll is still gunning for Ireland's first-ever victory over New Zealand later this month, before retiring at the end of the season.
Still smarting from being dropped for the British Lions' final and series-winning Test against Australia in the summer, the 34-year-old also feels he has a point to prove this autumn.
Maverick centre Pisi has made his name at Northampton, lighting up the Aviva Premiership in the past two years with a wide array of tricks and skills.
But the 27-year-old is every bit as physical as he is perceptive.
Pisi will want to test O'Driscoll on his outside shoulder, while the 125-cap O'Driscoll will demand the ball early, to control Ireland's backline attack.
An intriguing clash of Irish grit against Samoan wit.
JACK MCGRATH v LOGOVI'I MULIPOLA
Debutant loosehead prop McGrath is highly-rated by new Ireland head coach Joe Schmidt, who oversaw his development at Leinster.
First choice Cian Healy is on the bench to provide cover, but 24-year-old McGrath will want to show he needs no protection, especially when it comes to the scrum.
The set-piece will be critical to McGrath proving his international credentials.
The imposing 13-cap Mulipola is equally comfortable on either side of the scrum at club side Leicester Tigers, still one of European rugby's finest scrummaging exponents.
This battle could have pivotal bearing on the contest's course.