David Smith for Castres and Robbie Henshaw for Leinster both scored twice in a 24-24 draw in the Champions Cup on Friday.
Leinster now move onto 23 points, giving them an excellent chance of securing a home quarter-final.
The Irish province moved into an early 10-0 advantage via Henshaw’'s try and Johnny Sexton’'s penalty, but the hosts hit back, scoring 17 unanswered points.
Antoine Dupont and Smith both touched down while Julien Dumora added two conversions and a penalty.
It continued to be tight in the second half with Henshaw and Smith trading efforts. That gave the hosts a 24-17 advantage, but Dan Leavy went over to level matters and potentially give them a home match in the last eight.
After thrashing one French side last Friday, Leo Cullen’'s men set out with the intent to repeat the trick. They dominated the opening quarter and deservedly took a 10-0 lead through Sexton’'s penalty and Henshaw’'s opportunistic try.
With the hosts already out of the competition, that buffer may have opened the floodgates, but the Top 14 sides are different beasts at home.
Castres responded excellently and reduced the arrears when Dupont sniped around the fringes, evading two would-be tacklers and crossing the whitewash. Leinster’'s fly-half then departed with a leg injury and his replacement, young stand-off Ross Byrne, struggled to control the game.
That allowed the hosts to assert their authority and, after Dumora had levelled matters, Smith went over following superb work by Florian Vialelle for a 17-10 half-time lead.
The Irish province regained their composure at the start of the second period and duly equalised via Henshaw, who latched onto Adam Byrne’'s offload.
Castres were not finished though, and another close range effort from Smith put Leinster under pressure. As you would expect from the three-time winners, they responded magnificently and, in a wonderfully topsy-turvy encounter, Leavy levelled the game with 17 minutes remaining.
Pierre Berard was also serving time off the field after being sin-binned but the visitors failed to take advantage as both teams had to settle for a share of the spoils.
Tries: Dupont, Smith 2
Cons: Dumora 3
Yellow Card: Berard
Tries: Henshaw 2, Leavy
Cons: Sexton, Byrne 2
Yellow Card: McCarthy
Castres: 15 Pierre Berard, 14 Julien Caminati, 13 Afusipa Taumoepeau, 12 Florian Vialelle, 11 David Smith, 10 Julien Dumora, 9 Antoine Dupont, 8 Steve Mafi, 7 Alexandre Bias, 6 Yannick Caballero, 5 Rodrigo Capo Ortega, 4 Victor Moreaux, 3 Daniel Kotze, 2 Brice Mach, 1 Antoine Tichit
Replacements: 16 Jody Jenneker, 17 Mihaita Lazar, 18 Damien Tussac, 19 Loic Jacquet, 20 Anthony Jelonch, 21 Julien Seron, 22 Benjamin Urdapilleta, 23 Thomas Combezou
Leinster: 15 Isa Nacewa (c), 14 Adam Byrne, 13 Garry Ringrose, 12 Robbie Henshaw, 11 Rory O’Loughlin, 10 Johnny Sexton, 9 Luke McGrath, 8 Jamie Heaslip, 7 Josh van der Flier, 6 Jack Conan, 5 Devin Toner, 4 Ross Molony, 3 Tadhg Furlong, 2 Richardt Strauss, 1 Cian Healy
Replacements: 16 James Tracy, 17 Jack McGrath, 18 Michael Bent, 19 Mike McCarthy, 20 Dan Leavy, 21 Jamison Gibson-Park, 22 Ross Byrne, 23 Rob Kearney
Referee: Greg Garner (England)
Assistant Referees: Tom Foley (England), Paul Dix (England)
TMO: David Rose (England)