Scotland ended France's hopes of a Grand Slam with a 28-17 win on Sunday after the visitors had Mohamed Haouas sent off for punching shortly before half-time, while Saturday saw England defeat Wales 33-30 at Twickenham to clinch the Triple Crown to maintain their title hopes.
Meanwhile, the coronavirus continues to cast a shadow over the tournament, having already led to the postponement of both Ireland's match against Italy and Italy's scheduled finale against England in Rome.
France's defeat means that even if they beat Ireland in Paris on March 14, should that match go ahead, the title cannot now be decided next week.
Below AFP Sport looks at three things we learned from the fourth round of the 2020 Six Nations:
Indiscipline costs France dear again
France were leading Wales 19-10 in the World Cup quarter-finals last year when Sebastien Vahaamahinha was sent off for a blatant elbow on Aaron Wainwright in a match they ended up losing 20-19.
It seemed they had put such indiscipline behind them while winning their opening three matches this Six Nations but, leading Scotland 7-6, they saw prop forward Haouas land a clear punch on Jamie Ritchie, an equally clear red card offence as the one that saw Vahaamahina dismissed in Japan.
As Scotland came back and pulled clear, it was yet another reminder of how difficult it is to play a Test match when a man down.
"You just cannot afford to do that, you cannot afford to play with 14 men," said former Ireland lock Paul O'Connell, commentating on the match for the BBC.
Itoje has long been spoken of as a future England captain but there are other ways of leading from the front as the Saracens lock showed against Wales.
He was a central figure in so much of England's good play, making 15 tackles, and charging up field on the turnover after George North lost possession to set up the line-out - which Itoje then one himself - that led to the opening try for Anthony Watson.
As former England flyhalf Stuart Barnes wrote in the Sunday Times, "Itoje was instrumental in the moments that mattered most" and now seems certain to be one of the first names that Warren Gatland selects for the 2021 British and Irish Lions tour of South Africa.
Busy time for citing commissioner
Both England prop Joe Marler and coach Eddie Jones could find themselves in disciplinary trouble following Saturday's match.
Marler faces a minimum 12-week suspension after cameras caught him grabbing the genitals of Wales captain Alun Wyn Jones.
Eddie Jones, meanwhile, could have action taken against him for his post-match comments.
Jones was on thin ice when labelling the 75th-minute red card given to England centre Manu Tuilagi for an illegal 'no arms' tackle on North as "bizarre" but then went further by suggesting his side were playing against "16 men" at the finish.
The citing commissioner has 48 hours from the end of the match to recommend if any action should be taken.