How they man up: We rated the Leinster and Racing 92 starting XVs, management and bench impact to see who comes out on top
Leinster are bidding for a record-equalling fourth European title with opponents searching for an elusive first crown. Here's how they rate ahead of the game in Bilbao.
15 Rob Kearney - 8
A run of fitness has resulted in a reminder of his position as Ireland's greatest full-back. Superb in the air, strong on the ground and increasingly physical in defence. Rock solid.
14 Jordan Larmour - 7
Leinster's wild-card. A prodigious talent who is still in his breakout season, he can break teams wide open with a swivel of his hips but Racing will view his inexperience as an opening.
13 Garry Ringrose - 8
Thriving since his return to injury, his decision-making is every bit as impressive as his capacity to nail tough tackles or scythe through gaps. A potent weapon and unflappable under pressure.
12 Robbie Henshaw - 9
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Making up for a lost Grand Slam with a string of committed, skillful displays. Will find Henry Chavancy a physical match, but Henshaw offers so much more than excellent contact work.
11 Isa Nacewa - 7
In the last weeks of a great career and will need to bring his very best against the in-form Teddy Thomas who will capitalise on any opportunity if given. Brings calm and experience.
10 Johnny Sexton - 9
Up against an old team who never saw his best, Sexton is enjoying one of his finest campaigns and is Leinster's greatest threat. Capacity to identify and take chances is ruthless.
9 Luke McGrath - 7
Has not played since April 1, but his leadership and partnership alongside Sexton is an important component of the Leinster set-up. Racing will hope to pressure his pass.
1 Cian Healy - 9
Back to his best after a horrendous run of injuries, the loosehead is a destructive scrummager whose contribution around the park is unmatched.
2 Sean Cronin - 8
The form hooker in Ireland, his lineout work is solid and his carrying and tackling add a real physical edge to Leinster's threat.
3 Tadgh Furlong - 9
Now a global star who has yet to win a trophy for his province, his excellent set-piece work is complemented by his superb ball-work and relentless energy on both sides of the ball.
4 Devin Toner - 8
The lineout maestro is tasked with diffusing one of Racing's chief weapons. Often unheralded by the general public, but always trusted by the coaches. He has a big role to play.
5 James Ryan - 8
Has assumed the role of the engine in this Leinster team, carrying and tackling relentlessly in tandem while offering an offloading threat and set-piece assuredness.
6 Scott Fardy - 8
A spectacular success since arriving last summer, the experienced Australian sets the tone with his nugget breakdown work and leads by example in an excellent pack.
7 Dan Leavy - 9
Leinster's wrecking ball is the form player in the knock-outs, a big-game player who delivers an abrasive edge and will to win that seeps into his team-mates. Breakdown work will be key.
8 Jordi Murphy - 8
Has become an important cog in the wheel, offering an athletic carrying threat, a relentless work-rate and the capacity to win turnover ball.
Leo Cullen and Stuart Lancaster - 8
The coaches have had their team primed for every game of the campaign to date and have been able to win games in different ways, adapting to exploit opposition weaknesses.
Bench impact - 8
Fardy's versatility offers Cullen the chance to spring five international forwards into the fray with the all-Ireland front-row of James Tracy, Jack McGrath and Andrew Porter able to sustain the tempo, with Rhys Ruddock and Jack Conan excellent back-row options, Jamison Gibson-Park offers a change up at scrum-half, while Joey Carbery and Rory O'Loughlin cover a range of positions.
15 LOUIS DUPICHOT -7
A former footballer, the full-back is a clever attacker but doubts exist about his work under the high ball and Leinster will hope to isolate him as the last defender and get some joy.
14 TEDDY THOMAS - 9
The form winger in Europe right now, Thomas has the capacity to shred defenses with his sidestep and, while he has blown hot and cold at times during his career, he's in a rich vein of form.
13 VIRIMI VAKATAWA - 8
Used on the wing by France, he has the perfect combination of blunt force an craft with the ball. The problems may come without it where he is prone to switching off at times.
12 HENRY CHAVANCY - 8
Not thew greatest passer in the world but the Racing inside centre sets their defensive tone and is a key organiser in the backline., A relentless tackler who can carry hard.
11 MARC ANDREU - 7
The diminutive but combative former France winger is an attacking threat and is solid defensively. Will hope to test Jordon Larmour defensively.
10 PAT LAMBIE - 8
The Springbok looked close to retirement a year ago, but now he is keeping Dan Carter out of the Racing team with a clever passing game and reliable kicking option.
9 TEDDY IRABAREN - 6
Former Brive man is a breaking threat, but lacks the controlling influence of the captain Maxime Machenaud who misses out with injury.
1 EDDY BEN AROUS - 8
One of the best loosehead props in the game, the France international is a good scrummager who offers a serious threat at the breakdown and has a good engine.
2 CAMILLE CHAT - 8
The France hooker is in excellent form, offering solidity at set-piece, a strong carrying game, breakdown effort and good defense. An all-rounder.
3 CEDATE GOMES SA - 8
Keeping the massive Ben Tameifuna out of the side because of his superior engine and breakdown threat. Like Ben Arous, he is a modern prop who does far more than scrummage.
4 DONNACHA RYAN - 8
A familiar face to the Irish fans, Ryan has galvanised the Racing pack, offering an excellent work-rate that compliments the stars around him. Lineout work will be key.
5 LEONE NAKAWARA - 9
on his day he is the stand-out lock in the tournament, no one can do what he does with the ball. Munster figured out a way to limit his threat, if he can free his hands it's danger for Leinster.
6 WENCESLAS LAURET - 8
A dynamic option who offers an excellent lineout option, the France international will tackle all day and is part of a solid Racing back-row unit.
7 BERNARD LE ROUX - 7
The South African born France international is another who bucks the French club trend with a good engine and will take on Leavy on the deck.
8 YANNICK NYANGA - 8
The talk is the former France international will retire at the end of the season, which seems crazy given his brilliant form. A highly effective carrier who can get off the ground at lineout time.
LAURENT LABIT AND LAURENT TRAVERS - 8
Successful wherever they have been, the Racing co-coaches have put a structure and winning mentality into the French side and have gotten them performing consistently this season.
BENCH IMPACT - 7
Racing have gone for Joe Rockocoko ahead of the in-form Juan Imhoff, while scrum-half Antoine Gibert is inexperienced at this level. Any team that can spring Dan Carter (above) has the potential to change-up, but Racing have left some big hitters at home in search of continuity over impact.