France international Sofiane Guitoune scored twice as Toulouse moved to the summit of the French Top 14 on Sunday with a 29-16 win over struggling Grenoble.

Despite his impressive form this season, Guitoune is not among the Toulouse players selected by Jacques Brunel for France's Six Nations squad.

The hosts took top spot for the first time this term after season-long leaders Clermont lost at Castres on Saturday.

? Les Stadistes peuvent avoir le sourire après leur victoire bonifiée lors de #STFCG !
Encore félicitations à tous et rendez-vous à E. Wallon le 23 février à 18h pour #STMHR ! ?⚫ pic.twitter.com/XtOvWyFNTY

— Stade Toulousain (@StadeToulousain) January 27, 2019

Grenoble's points came from the boot of flyhalf Mathieu Ugalde and a try by hooker Mike Tadjer, and they remain in 12th, four points above the relegation playoff place.

Ugalde opened the scoring for Grenoble with the first of his three penalties after a turgid opening 20 minutes on a muddy surface at Stade Ernest-Wallon.

Guitoune, 29, whose last Test match came during the 2015 Rugby World Cup, dotted down six minutes later, making the most of a distracted defense by taking a quick tap from 10 meters out and diving over.

Ugalde added Grenoble's second penalty after half an hour before Toulouse pressure delivered another touchdown. A powerful scrum was followed by a deft offload from the influential Guitoune to sendteenager Matthis Lebel in at the corner.

The visitors' flyhalf slotted his final three-pointer of the game shortly after the break but Toulouse dominated the rest of the fixture.

Guitoune kept his best until the hour-mark, profiting from another quick tap penalty, this time by scrum-half Sebastien Bezy, to secure his eighth touchdown of the season.

Hooker Clement Castets, 22, clinched the bonus point with a quarter of an hour remaining.

Tadjer scored a consolation effort seconds before the full-time whistle.

Guitoune praised the performances of the younger members of the squad who stepped up with seven players away on French duty.

"For sure it's our strength, we have a good group, it's not massive but we have good youngsters. It's been the strength of Toulouse during the past years to produce good youngsters," he said.

"When you see Matthis Lebel and Arthur Bonneval it bodes well for the future," he added.

Clermont Slip Without Six Nations Studs

French Top 14 champions Castres ended league leaders Clermont's 13-game unbeaten run with a gritty 24-16 victory on Saturday.

French wingers Armand Battle and Martin Laveau scored tries for the hosts as the visitors lost for the first time since October 6.

Peceli Yato crossed in the first half for Franck Azema's side who were without six players who are part of France's squad preparing for the Six Nations.

Their second-half efforts which included a touchdown for Remy Grosso and a Greig Laidlaw penalty goal proved futile.

The hosts dominated the opening half an hour of play and claimed the early lead as winger Battle crossed for only his second try of the campaign.

Benjamin Urdapilleta added a penalty goal before Castres' second try to consolidate their control of proceedings at Stade Pierre-Fabre. Youngster Laveau dotted down as Argentina international Urdapilleta made the most of an overlap to find the 22-year-old in space on the right wing. 

Clermont's reaction came with their first possession inside Castres' 22-meter line as Fiji back-rower Yato powered over from the back of a scrum two minutes from half-time.

Referee Jerome Garces, who will oversee the Ireland vs England Six Nations match on February 2, validated the five points after help from the television match official.

The visitors started the second half perfectly as former Castres winger Grosso intercepted a loose pass to run in from inside his own half unopposed.

Urdapilleta slotted two extra penalty goals before Scotland scrumhalf Laidlaw brought the teams within five points just after the hour mark with an effort of his own.

Laidlaw missed the chance to close the gap to two points as his shot at goal glanced to the right of the posts before France international Rory Kockott sealed the win with 10 minutes remaining with his tenth penalty of the Top 14 campaign.

Clermont coach Azema criticized his team's performance in the opening 40 minutes.

"We saw a small Clermont today. We didn't play with the necessary intensity especially in the first half when Castres had 70% of possession," he said. "Is our first place under threat? Yes, but top spot never gives you the title."

Captain Damien Chouly shared his boss' thoughts.

"It took us a half to get into the game. We didn't have the ball in the first half and then had to play catch up in the second," he said. 

© Agence France-Presse