Andy Farrell has called up five uncapped players into his first Ireland squad, with Johnny Sexton confirmed as the team's captain.
Louis Rees-Zammit, the 18-year-old Gloucester flyer, could make his Wales debut in the Six Nations in a new era under Wayne Pivac.
Gregor Townsend has turned to Stuart Hogg to lead Scotland in the Six Nations following Greig Laidlaw's international retirement.
Cobus Reinach could be set to join Montpellier after announcing he will leave Northampton Saints following three seasons at the club.
The Six Nations kicks off next month and England will have a new coaching line-up in place for the tournament.
Alberto Sgarbi has not played for Italy since 2014 but was named in Franco Smith's first squad selection on Monday.
A thrashing of Lyon ensured Leinster made it five wins from five in the European Champions Cup, while Racing 92 reached the last eight.
Rhys Carre's early red card made life difficult for Saracens, but they still defeated Ospreys in the European Champions Cup.
La Rochelle kept their hopes of progressing in the European Champions Cup alive by beating Sale Sharks, while Harlequins edged out Bath.
Sam Underhill, Jack Walker and Max Wright have all signed three-year contracts to remain at Bath.
Saracens have brought in lawyer Neil Golding as their new chairman after Nigel Wray stepped down.
Jack Maddocks has returned to New South Wales to join the Waratahs after three seasons with the Rebels.
Joey Carbery has suffered another injury blow and will play no part in Ireland's bid to regain the Six Nations title.
Charles Ollivon only has 11 caps to his name but the Toulon back-row will captain a new-look France during the Six Nations.
Worcester's former Hurricanes forward Michael Fatialofa is recovering from a neck injury suffered in the Premiership match against Saracens.
Saracens may have to offload players to comply with salary-cap regulations, with the club running a "scoping exercise" to reach a decision.