Six Nations leaders Wales are now the only team who can complete a Grand Slam after England ended French hopes of a clean sweep, with Ireland moving into second place after surviving a Scotland fightback at Murrayfield.
Here, AFP Sport looks at three talking points to have emerged from this weekend's fourth-round matches:
Curry's case for the defence
Maro Itoje's try four minutes from time saw England come from behind to beat France 23-20 but their win at Twickenham also owed much to their improved defensive discipline.
It took England some 25 minutes before they conceded their first penalty on Saturday and their resilience was summed up by an energy-sapping piece of play involving flanker Tom Curry on the stroke of half-time.
France were leading 17-13 and a third try at that point might well have proved decisive for the visitors.
But after the ball had been in play for over two minutes, with possession changing hands six times, Curry denied France by making a turnover a metre from his own line.
In the context of a close match, the back-row's intervention was just as important as any try.
Biggar shows his all-round game
Dan Biggar may be renowned for the quality of his kicking but Wales' 48-7 thrashing of Italy in Rome on Saturday was a reminder that there is more to the fly-half's game than just a powerful boot.
Admittedly, a match against an Italy side suffering a 31st successive Six Nations defeat was the ideal opportunity for Biggar to demonstrate his handling skills, with an inch-perfect long pass to Josh Adams sending the wing in for the first of Wales' seven tries.
But it was also a reminder to France, now the only team standing between Wales and a Grand Slam, that they cannot just stand off Biggar.
Jones makes his mark
Scotland were left frustrated by a 27-24 loss to Ireland on Sunday.
It might have been worse, however, given Ireland were 14 points ahead approaching the final quarter.
But if the aim of bringing a replacement off the bench is to change the game, then Scotland coach Gregor Townsend could at least be pleased with the impact made by Huw Jones with Ireland well-ahead at 24-10.
Following a quick free-kick off a scrum, Bayonne-bound centre Jones sliced through Ireland's defence, shrugging off tackles from James Lowe and Hugo Keenan for his 11th try in 29 Tests.
