A Six Nations without fans was once an implausible concept.

Hard-fought wins may not be rewarded by roaring crowds, but with a British and Irish Lions tour due to begin in five months - coronavirus permitting - the home nations still have plenty to play for.

If the past year has taught us anything, it is to expect the unexpected so who knows what the world will be like come the end of the tournament in March?

But here is a look at the title contenders, players to watch and the situation with fans as the championship gets set to begin on Saturday.

Who will win the 2021 Six Nations?

England won the protracted 2020 tournament in part thanks to a losing bonus point earned in Paris on the opening weekend - a fact that drew some criticism at the time.

This time around Eddie Jones' side - Autumn Nations Cup champions in December - are favourites to win the tournament again, with a France team packed with youthful star power their main rivals.

England's fourth-round match at home to France on 13 March could be the pick of the games - part of a tough run for Les Bleus which also includes a tricky trip to Dublin in round two.

The 2020 champions are perhaps the worst hit by Covid. Head coach Jones missed the start of England's training camp along with two other coaches because he was self-isolating.

Assistant coach Jason Ryles was expected to join the squad but in January decided it was not a good time to relocate to England from Australia.

Jones has also been restricted to a 28-man squad to reduce the risk of spreading coronavirus.

France coach Fabien Galthie may have a wealth of players to choose from but he will have to make do without injured fly-half Romain Ntamack, who impressed alongside scrum-half Antoine Dupont in last year's tournament.

But as Les Bleus proved when they were forced to play the Autumn Nations Cup final without many of their regular starters, there are many young players waiting in the wings ready to step up.

Can returning Russell inspire Scotland?

Racing 92 star Finn Russell's autumn return to the Scotland set-up following exile for breaching team protocol was shortlived after he sustained an injury at the end of October.

But the fly-half, who many fans hope will start for the Lions, is fit again and has been named in Gregor Townsend's 35-man squad.

Scotland enjoyed mixed results at the end of last year, winning their final Six Nations game before finishing fourth in the Autumn Nations Cup, but Russell's return offers hope for 2021.

Ireland beat Townsend's side to finish third in the autumn tournament, giving head coach Andy Farrell a satisfying end to the year after lacklustre displays against England and Georgia.

Wales head coach Wayne Pivac has said his side has what it takes to win the Six Nations, despite losing four games and finishing fifth in 2020.

The New Zealander has won three out of 10 competitive games since he took charge in late 2019 and has turned to more experienced players like flanker Dan Lydiate in an attempt to get out of the rut.

Once again, Italy will have a battle on their hands to win a game and a possible final appearance for legendary number eight Sergio Parisse could be the most exciting part of their campaign.

Could fans return before the end of the tournament?

The championship will begin in empty stadiums with all countries under some form of coronavirus restrictions.

Scottish Rugby said in January access to matches at Murrayfield against Ireland and Italy - on 14 and 20 March - was "under current review", with Scotland's first two games against England and Wales behind closed doors.

Two thousand England fans were allowed to return to Twickenham for the side's final Autumn Nations Cup game under tier two coronavirus restrictions, but it is unclear whether the country will return to a similar tier system following lockdown.

Wales are yet to play in front of fans since the pandemic began as the Welsh government did not follow England in allowing supporters back in certain tiers.

Supporters were not allowed at Ireland's last home game in December and fans in Dublin continue to seem an unlikely prospect after the country returned to a full lockdown at the end of 2020.

The French government decreed that its clubs should not play in European Cup competitions in January but it is hoped strict travel quarantine rules will not affect the Six Nations, with exemption applications for sides playing in France pending.

Either way welcoming fans back to games may not be high on the agenda, while Italian sport has not seen crowds since October.

Who are the ones to watch?

Scotland's latest recruit Cameron Redpath represented England Under-20s and has previously been called up by Eddie Jones without winning a full cap.

Former British and Irish Lions wing Ugo Monye described the 21-year-old Bath centre as "the real deal" and expressed disappointment that Redpath - son of former Scotland captain Bryan - would not be pulling on an England jersey this spring.

Wales scrum-half Tomos Williams may not be counted as a young gun at 26 with 20 caps to his name but he could be a dark horse for the nine jersey on the upcoming Lions tour.

Conor Murray and Ben Youngs are also in the running but there does seem to be a slight opening at scrum-half that Williams could take advantage of if he can see off competition from compatriot Gareth Davies.

When France were without several key players in the autumn, sevens wing Gabin Villiere was one of those who stepped in.

He impressed with scything runs and expect more of the same if Galthie gives him his chance again.

Wasps back Paolo Odogwu has already elicited praise from Eddie Jones before even earning an international cap.

The England head coach said Odogwu has an instinct "you can't coach". That has been evident in the Premiership this season, where he leads the league in clean breaks.

New Zealand-born Ireland wing James Lowe left fans wanting more after an impressive debut against Wales in the Autumn Nations Cup.

The 28-year-old was rewarded with his first international try and he will be looking to add to that tally in the coming weeks.

Italy head coach Franco Smith's team has an average age of just 24 and sitting at the lower end of the scale is 20-year-old fly-half Paolo Garbisi.

Last year, Garbisi went from playing for club Petrarca in the Italian league to earning a first start for his country and he is expected to continue on that steep trajectory in 2021.

Will it be entertaining?

Questioning the entertainment value of a Six Nations may seem strange, but there were complaints about the style of play used in the Autumn Nations Cup.

While there were occasional wonder tries - like Jonny May's effort against Ireland - some games saw few offloads and excessive use of a repetitive kicking game.

A sudden-death thriller between England and France did bring the autumn tournament to an exciting end and more of the same would be a welcome distraction over the next two months.

As we approach the mid-point in the four-year World Cup cycle, fans will be hoping coaches use this Six Nations as a chance to experiment with new styles of play.

A Lions tour looming may well entice a bit more flair out of home nations players, meaning they light up stadiums with or without fans.