Ireland are on a record run of 12 consecutive home wins as they prepare to host England on the opening weekend of the Six Nations.
Sam Johnson will make his international bow when Scotland start their Six Nations campaign against Italy.
Stuart Hogg believes Scotland are on the cusp of "something incredibly special" as they attempt to improve on a third-placed finish.
Warren Gatland's final year in charge of Wales promises to be exciting, with the team hitting form ahead of the Six Nations and a World Cup.
A look at every team competing in the 2019 Six Nations championship, as Ireland look to follow up their Grand Slam triumph.
Stuart Hogg believes Scotland are on the path to "something incredibly special" and can win the Six Nations this year.
Scotland will be without Hamish Watson when their Six Nations campaign begins on February 2.
Quinn Roux has been called up to the Ireland squad for their first two Six Nations matches after Tadhg Beirne was ruled out.
Hamish Watson has dropped out of Scotland's Six Nations squad with a hand injury, while four players have been called up.
Seven uncapped players feature in Scotland's squad for the Six Nations, with three of those selected at hooker.
Scotland's work ethic and persistence pleased Gregor Townsend as they ended 2018 with victory over Argentina at Murrayfield.
Greig Laidlaw kicked three penalties before Sean Maitland's try as Scotland beat Argentina 14-9 at Murrayfield.
Gregor Townsend has again shaken up his Scotland team, making eight changes for the clash with Argentina.
Handre Pollard scored 18 points as South Africa became only the second side in 12 matches to beat Scotland at Murrayfield.
With Faf de Klerk on club duty with Sale Sharks, Embrose Papier will make his first South Africa start on Saturday.
Gordon Reid will make his first Scotland appearance since March as one of six changes for their clash with South Africa.