Heineken Champions Cup: Courtney Lawes a doubt for Six Nations as he limps off in Northampton's defeat | Harlequins, Leinster and Gloucester progress

England flanker Courtney Lawes' participation in this season's Six Nations is in doubt after he limped off in the 29th minute of Northampton's 31-13 defeat to La Rochelle in the Heineken Champions Cup.

Lawes has been beset with injuries of late and if he is ruled out it will be a serious blow to England's chances of a successful campaign.

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Northampton head coach Phil Dowson said: "Courtney doesn't appear to be downbeat, he never is, but he felt
he couldn't continue.

"His calf tightened up, he hasn't had an issue with it before but he will need to see the physio tomorrow and possibly have a scan so it's fingers crossed."

The loss of Lawes completed a miserable afternoon for Saints, as centre Fraser Dingwall was sent off for a high challenge just 10 minutes after the 33-year-old had left the field, and lock Lukhan Salakaia-Loto also received a red card in the dying moments.

With these two key departures, Saints had no chance of competing with the reigning champions so they fell to their fourth defeat in the competition, which left them rooted to the bottom of Pool B with just a single point.

Quentin Lespiaucq-Brettes scored two tries for La Rochelle, Levani Botia, Ulupano Seuteni and Gregory Alldritt the others with Antoine Hastoy kicking three conversions.

Tom James scored a try for Northampton with Fin Smith adding two penalties and a conversion.

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Harlequins 39-29 Sharks

Harlequins took advantage of crisp conditions to end their victory drought with a 39-29 win against the Sharks that propels them into the Heineken Champions Cup knockout phase.

Danny Care celebrated his 350th appearance for Quins with a try and there were also touch downs for Alex Dombrandt, Cadan Murley, Stephan Lewies and Nick David in a comfortable bonus-point triumph.

The 2021 Gallagher Premiership champions revelled in the sunshine at Twickenham Stoop to continue the revival begun against Racing 92 a week earlier, clinching their first victory since December 18.

They led 21-8 in the first 20 minutes alone and having faced a spirited comeback from a Sharks team featuring South Africa stars Siya Kolisi, Eben Etzebeth, Ox Nche and Lukhanyo Am, they accelerated clear once more in the third quarter.

Leinster 36-10 Racing 92

Leinster advanced to the Heineken Champions Cup's last 16 as top seeds following a runaway 36-10 win over Racing 92 at the Aviva Stadium.

The Irish province's unbeaten record looked under threat until they cut loose with unanswered tries from Hugo Keenan, Josh van der Flier, Jimmy O'Brien, and captain Garry Ringrose.

A tight first half had ended 7-5 in Leinster's favour, some poor discipline from the hosts, coupled with Janick Tarrit's maul try, clouding out the early promise offered by O'Brien's 14th-minute score.

Christian Wade was released by Finn Russell for the visitors' second try, but the Pool A pacesetters regained their form to earn a fourth straight bonus-point victory and knock the French side out of the competition.

Ulster 22-11 Sale Sharks

Second-half tries from Rob Herring and Duane Vermeulen put Ulster through to the European Champions Cup knockout stages as a 22-11 win over Sale Sharks also ended their losing run.

It was the Irish province's first win in the pool stages and knocked Sale out of the competition after the Gallagher Premiership side had beaten Ulster 39-0 in the opening round.

Rob Lyttle also scored a try for Ulster, who now face Leinster away in the round of 16, with John Cooney kicking two conversions and Nathan Doak a penalty in a tense clash which saw the home team lead 8-6 at half-time.

Sale scored one try through Tom Curry and kicked two penalties from Robert du Preez.

Bordeaux-Begles 17-26 Gloucester

Two tries from George McGuigan proved vital as Gloucester moved into the knockout stages of the Heineken Champions Cup with a sensational 26-17 victory over Bordeaux-Begles.

The hooker, who has been named in England's Six Nations squad by new head coach Steve Borthwick, crossed twice from driving line-outs as Gloucester completed the double over the French outfit to be the final qualifier from Pool A in the last 16.

Bordeaux knew they could not progress to the knockout stages of the showpiece club tournament but would have been able to qualify for the latter rounds of the second-tier Heineken Challenge Cup with a win.

Exeter Chiefs 40-3 Castres Olympique

Exeter secured a home tie in the Heineken Champions Cup round of 16 after beating Castres 40-3 at Sandy Park.

The Chiefs required a bonus-point victory to guarantee a top-four finish in Pool A, and they duly delivered despite never remotely hitting top gear.

They were helped by Castres' woeful indiscipline that saw number eight Feibyan Tukino sent off for a dangerous tackle just before half-time, while flankers Baptiste Delaporte and Mathieu Babillot were both yellow-carded, along with prop Aurelien Azar.

It meant that the visitors were briefly reduced to 12 players, yet Exeter did not secure a five-point maximum until seven minutes from time through a second penalty try.

England internationals Henry Slade, Sam Simmonds and Jack Nowell also touched down, as did Wales forward Christ Tshiunza, in addition to a first-half penalty try, with Slade kicking two conversions and Joe Simmonds one.

Castres were restricted to an early Ben Botica penalty, and while it was a game that will not live long in the memory, 2020 European champions Exeter will feel relieved to have got the job done.

DHL Stormers 30-16 Clermont Auvergne

The DHL Stormers booked a place in the Heineken Cup last 16 with a bonus-point 30-16 victory over Clermont Auvergne.

Four tries in the second half, with Evan Roos, Herschel Jantjies, Dan du Plessis, and Deon Fourie crossing the whitewash, helped the Stormers fight back after going 6-3 down at half time.

The first 40 was a scoreless affair, with penalties from Clermont's Anthony Bellau and Stormers' Kade Wolhuter the only scores on the board.