Castres and Racing 92 close in on Top 14 playoff spots
Lyon sealed a Top 14 playoff berth when they beat La Rochelle 29-19 on Saturday.
The loss dropped La Rochelle to sixth in the standings, behind Castres and Racing 92, who both won earlier in the day.
Racing thrashed relegated Perpignan, 52-14, to secure a bonus point and jump two places while Castres hung on to a 17-10 victory at Agen, to remain in fifth.
"It was important to win with the bonus," said Laurent Travers, the Racing coach.
With one round to go, Lyon have 70 points and are certain to finish third and enjoy a home quarterfinal.
Castres and Racing both have 69 points and La Rochelle have 66. All three can be caught by Montpellier who are on 61 and face Stade Francais on Sunday.
In Lyon, Australian flanker Liam Gill scored the only try as Lyon built a 16-9 half-time lead.
A touchdown by winger Eliott Roudil brought the visitors level early in the second half.
But Kiwi centre Charlie Ngatai restored the home advantage and a drop goal by flyhalf Jonathan Wisniewski, who finished with 19 points, gave the home side a 10-point cushion.
In the final round, Montpellier are at Clermont, Castres host Toulon, Racing visit Agen and La Rochelle face Bordeaux Begles at home.
"Next week, it is the match of fear," said Roudil.
Castres, the French champions, had lost their last two games, both at home.
"We are happy with the win after two disappointing losses," said Castres manager Christophe Urios, adding that he would have prefered to gain a bonus point.
Castres started strongly in the wind and rain and built a 17-3 lead by the 44th minute with tries by prop Wilfrid Hounkpatin and lock Loic Jacquet.
Benjamin Urdapilleta, who had kicked eight points, received a yellow card in the 59th minute and was still off the field when home captain Antoine Miquel touched down leaving Castres defending a one-score lead for the last 13 minutes.
"It would have been a hold up," said Agen coach Mauricio Reggiardo, who will take over at Castres next season. He went on to praise his future players saying they "played in champion mode."
Racing ran riot at relegated Perpignan scoring all eight tries in the first 51 minutes.
Wing Louis Dupichot and Irishman Simon Zebo, who was at fullback, each scored a hat trick of tries. All Black lock Dominic Bird and Scotland flyhalf Finn Russell each added one.
"In the second half we were less precise and spent too much time admiring our own brilliance," Travers said.
He added that he was awaiting news of Zebo, who went off after 51 minutes, had suffered a blow to the ribs.
If the table does not change, the Racing and Castres would meet in the quarterfinals with Racing enjoying home advantage.
When they met in Castres in the previous round, Racing won. Last year, Castres won an away quarterfinal on their way to claiming the title.
"If you play at Racing, it's to win titles," Duplichot said.
? 2019 AFP