Saints see red as Leinster smash them

Hartley, who had started on the bench after year-end Test duty, replaced Mikey Haywood after 50 minutes for his 50th appearance in the tournament.

However, just six minutes later, the hooker was heading off in disgrace for aiming a wild punch at the head of Leinster flank Sean O'Brien.

As well as helping to condemn 2000 champions Northampton to a second defeat in three games in Pool Four and help Leinster cement top spot, the incident could dent Hartley's hopes of captaining the British and Irish Lions in New Zealand next year.

The defeat capped a miserable spell for Northampton who had come under fire for allowing their Welsh wing George North to continue playing in a Premiership fixture last weekend after having been knocked temporarily unconscious.

Leinster's new Irish star Garry Ringrose scored the only try of the first half after just two minutes when he sprinted clear following a clever shimmy and dummy from fullback Rob Kearney.

Skipper and wing Isa Nacewa popped over the conversion for 7-0 which soon became 10-0 for the three-time champions when the 34-year-old New Zealander kicked a penalty.

Northampton's only points of the first period came via a 20th-minute penalty from the metronomic boot of Stephen Myler.

Northampton were level at 10-10 in the 45th minute thanks to a try from Samoan wing Ahsee Tuala who finished off a move inspired by former Munster centre JJ Hanrahan.

Myler added the extras before Nacewa hit a monster penalty to restore Leinster's lead at 13-10.

That signalled the entrance of Hartley but he and his fellow forwards were soon overpowered when O'Brien was barged over the try line thanks to the supporting muscle of No8 Jamie Heaslip.

Nacewa again hit the extras for 20-10 before Hartley's brief appearance came to an end for his right-handed haymaker at the head of O'Brien.

Referee Jerome Garces had no hesitation in reaching for the red card as Hartley trotted off much to the dismay of watching England coach Eddie Jones.

Leinster scored a third try when debutant Rory O'Loughlin outjumped an inattentive Ben Foden to dot down a clever crossfield kick from Ross Byrne.

Nacewa missed the extras but Leinster soon made their one-man advantage count when Jamison Gibson-Park skipped through a weary Northampton defence for a 32-10 lead and a bonus point. Nacewa added the fifth try in the last minute.

On Saturday, defending champions Saracens will seek to make it 12 straight wins in Europe when they take on English Premiership rivals Sale in Pool 3.

Saracens, just two wins away from equalling Munster's record of 13 successive tournament victories set between 2005 and 2007, have not lost in Europe since they were beaten 13-9 by Clermont in the 2015 semi-final and last season became the first side to win all nine matches to take the title.

The other game in Pool 3 pitches Scarlets against Toulon.

Other top match-ups see Leicester, in Pool One, put their two-game unbeaten record on the line at Thomond Park against Munster in a re-run of the 2002 Final.

Top 14 leaders Clermont head to Belfast to face Ulster in Pool Five while Toulouse will be seeking their first victory in Pool Two, away at Italians Zebre.

The scorers:

For Northampton Saints:

Try: Tuala

Con: Myler

Pen: Myler

For Leinster:

Tries: Ringrose, O'Brien, O'Loughlin, Gibson-Park, Nacewa

Cons: Nacewa 3

Pens: Nacewa 2

Yellow card: George Pisi (Northampton Saints, 77 – foul play, head high tackle)

Red card: Dylan Hartley (Northampton Saint, 57 – foul play, swinging arm tackle on an opponent)

Teams:

Northampton Saints:  15 Ben Foden, 14 Ken Pisi, 13 Luther Burrell, 12 JJ Hanrahan, 11 Jamie Elliot, 10 Stephen Myler, 9 Nic Groom, 8 Louis Picamoles, 7 Tom Wood (captain), 6 Jamie Gibson, 5 Courtney Lawes, 4 Michael Paterson, 3 Paul Hill, 2 Mikey Haywood, 1 Alex Waller.

Replacements: 16 Dylan Hartley, 17 Ethan Waller, 18 Gareth Denman, 19 Api Ratuniyarawa, 20 Teimana Harrison, 21 Tom Kessel, 22 George Pisi, 23 Ahsee Tuala.

Leinster: 15 Rob Kearney, 14 Adam Byrne, 13 Garry Ringrose, 12 Robbie Henshaw, 11 Isa Nacewa (captain), 10 Joey Carbery, 9 Luke McGrath, 8 Jamie Heaslip, 7 Josh van der Flier, 6 Sean O'Brien, 5 Hayden Triggs, 4 Devin Toner, 3 Tadhg Furlong, 2 Sean Cronin, 1 Jack McGrath.

Replacements: 16 James Tracy, 17 Cian Healy, 18 Michael Bent, 19 Rhys Ruddock, 20 Jack Conan, 21 Jamison Gibson-Park, 22 Ross Byrne, 23 Rory O'Loughlin.

Referee: Jérôme Garcès (France)

Assistant referees: Adrien Descottes (France), Sebastian Cloute (France)

TMO: Eric Gauzins (France)

Agence France-Presse