Peter O'Mahony has been banned for the next three rounds of Six Nations games following his red card in Ireland's opening defeat to Wales.

O'Mahony was dismissed in the 14th minute of Ireland's 21-16 loss in Cardiff after leading with his elbow to the head of Tomas Francis while attempting a clearout.

The flanker can now not feature for Ireland again until their final match of the tournament, which sees them host England on March 20.

O'Mahony admitted to dangerous play in the ruck and that his actions merited a red card during a disciplinary hearing.

The disciplinary committee deemed the entry point for his offence to be a six-week ban, but halved that suspension after taking into account O'Mahony's record and conduct in the hearing.

In a statement, Six Nations organisers said: "The committee considered all the relevant evidence, including the player's oral evidence, together with the clips of the incident.

"In assessing the seriousness of the offending, the committee found that the offending was reckless."

Ireland will attempt to bounce back on Sunday when they welcome France to Dublin.

Wales are set to be without four players for their Six Nations clash with Scotland next Saturday as they count the cost of a hard-fought win over Ireland.

Wayne Pivac's men had to recover from a first-half blip as they surrendered a 6-0 lead to 14-man Ireland after the visitors had Peter O'Mahony sent off for leading with the elbow to the head of Tomas Francis.

Ireland went into the break 13-6 ahead despite their personnel disadvantage, but tries from George North and Louis Rees-Zammit proved enough for Wales to claim a 21-16 victory.

However, it was something of a pyrrhic triumph with Johnny Wiliams and Hallam Amos poised to miss the visit to Murrayfield with head injuries, while Pivac also ruled out Tomos Williams with a hamstring issue and Dan Lydiate, who is suspected to have a knee ligament problem.

"We've picked up a few injuries so we're looking at those now, we'll make a better assessment [on Monday]," Pivac said.

"We're sort of counting the walking wounded after that one.

"The six-day turnaround means certain players won't be playing for us, two with the head knocks. A six-day turnaround means any head knocks, you're gone.

"Unfortunately we lose a couple of players straight away. We'll see how the rest of the squad is [on Monday] and look at what sort of side we can put together on Tuesday.

"Johnny Williams went off for a HIA [head injury assessment] and didn't come back on. The other one was Hallam Amos who took a late knock too. Those are the two head knocks.

"Then we've got a hamstring for Tomos Williams – we're hoping that's not serious but it won't turn round in six days, I wouldn't have thought."

Pivac added of Lydiate: "We're going to get that scanned but it's not looking too good. It could be an ACL but we'll get that scanned for a definite result.

"It's very disappointing for Dan and he's very disappointed in the changing room right now."

Ireland coach Andy Farrell, meanwhile, expressed confidence O'Mahony will make amends for his indiscretion, telling BBC Sport: "We've seen red cards for that in the past haven't we?

"I think we've seen yellow cards for other incidents that didn't quite go our way.

"He's been around enough a long time and he's gutted. He's been a pretty stalwart player for us in the past and he'll continue to do so in the future."

Wales took advantage of Peter O'Mahony's early dismissal and survived a fightback from 14-man Ireland to start their Six Nations campaign with a 21-16 win in Cardiff.

O'Mahony was sent off in the opening 15 minutes for contact to the head but Andy Farrell's men overcame their disadvantage in personnel to lead 13-6 at the interval.

But tries from George North and Louis Rees-Zammit turned the contest back in Wales' favour, with Ireland unable to produce another riposte.

The visitors were also dealt a late blow as Johnny Sexton went off with a head injury, giving Farrell plenty to worry about ahead of next week's clash with France.

Ireland were pinned for side entry at the ruck in the opening five minutes, giving Leigh Halfpenny the chance to boot Wales into a three-point lead.

O'Mahony was guilty of a much more serious infraction in the 14th minute, the flanker seeing red for leading with the elbow to the head of Tomas Francis as he attempted a clearout.

Wales, who earlier lost Dan Lydiate to a leg injury, doubled their advantage four minutes later through Halfpenny's trusty right peg.

However, Ireland enjoyed the majority of possession and territory thereafter in the first half and were rewarded for an extremely spirited fightback.

A pair of Sexton penalties drew Ireland level and a break from Robbie Henshaw then enabled Tadhg Beirne to dive over and give them a seven-point lead to defend.

Wales saw scrum-half Tomos Williams suffer a hamstring injury on the stroke of half-time but his absence did not prevent the hosts from getting back into the contest.

North capitalised after a series of Ireland handling errors to surge through a gap on the right and touch down, but Halfpenny misjudged the conversion attempt.

But that instance of profligacy from the tee did not prove costly as Rees-Zammit produced a stunning finish in the right-hand corner to put Wales back in front.

Halfpenny atoned for his earlier miss with a superb kick from the sideline to add the extras before knocking over a more routine kick as a penalty made it 21-13.

Billy Burns trimmed the deficit back to five points shortly after Sexton's exit but he failed to find touch with a penalty as he attempted to push Ireland to the five-metre line in stoppage time as Wales survived a dramatic final push from the visitors.

England start their quest to retain the Six Nations title against Scotland on Saturday just over three months after they were crowned champions. 

The Red Rose dethroned Wales at the end of October, pipping France on points difference in a dramatic finale to a tournament that ended almost nine months after it started due to the COVID-19 pandemic. 

Eddie Jones' side are favourites to win the competition again, but Les Bleus are also well fancied to end an 11-year wait for Six Nations glory and face Italy in the first match. 

England do battle with Scotland for the Calcutta Cup at Twickenham, with Wales and Ireland locking horns in Cardiff on Sunday. 

Ahead of the opening round, we preview the upcoming matches with help from Opta.

ITALY v FRANCE

FORM

France have won 19 of their 21 previous Six Nations matches against Italy (L2), including their last seven in a row. Their two defeats in that time both came in Rome, in 2011 and 2013.  

Italy have lost their last 27 Six Nations matches, the longest losing streak in the history of the competition. Their last victory came at Murrayfield against Scotland in 2015, while they have not won at home since 2013. 

Les Bleus achieved a cumulative points difference of +31 in the first 20 minutes of their 2020 Six Nations matches. No other side managed a positive double-digit points difference in that period of matches, but Italy had a -39 difference. 

ONES TO WATCH

France wing Teddy Thomas scored a try in his last Test against Italy and is capable of lighting up the tournament. He can get off to a storming start in Rome.

Paolo Garbisi caught the eye at fly-half last year after being handed his debut against Ireland in October. Hopefully for his country, there is still much more to come from the 20-year-old.

ENGLAND v SCOTLAND

FORM

The last time England hosted Scotland in the Six Nations they drew 38-38 two years ago. Scotland clawed back the biggest ever half-time deficit (-24 pts, 7-31) by a side to avoid defeat in the tournament’s history, almost snatching victory before a late George Ford try denied them. 

Scotland have never beaten England at Twickenham in the Six Nations (D1, L9), their last victory against them the Red Rose at the London venue came in 1983 in the Five Nations (22-12).  

Gregor Townsend's side concluded the 2020 edition by winning their last three games in a row, their best run in the Championship since Italy joined in 2000. 

ONES TO WATCH

England captain Owen Farrell has scored exactly 1,000 Test points, one of just six men to reach that milestone. He is just four points away from reaching a century against Scotland.

Finn Russell returns to the Scotland side and the creativity provided by the fly-half will be key for Townsend's men.

WALES v IRELAND

FORM

Wales have lost their last two home games in the Six Nations, the last time they suffered three consecutive defeats at home was in 2002-03. Wayne Pivac's side have lost their last four games in the competition, their worst streak since 2006-07 (L5).  

No team scored more tries than Ireland in the Six Nations last year (17, along with France), four of those were launched from the back of a scrum. Wales (2) were the only other side to score multiple tries following a scrum.  

Ireland scored seven tries in the final quarter of their fixtures in 2020, more than any other side. Wales, meanwhile, scored the joint-second most in that period (6, level with England). 

ONES TO WATCH

Louis Rees-Zammit turned 20 this week and the Wales wing can celebrate in style with a livewire display at the Principality Stadium.

Ireland centre Garry Ringrose had terrible luck with injuries last year, but he is ready to fire on all cylinders in 2021.

French Rugby Federation (FFR) president Bernard Laporte says there is "no question" that the Six Nations will be staged this year.

The Telegraph this weekend reported that the tournament was in doubt after the French sports ministry imposed a ban on playing cross-border elite sports with clubs from the United Kingdom due to a new strain of coronavirus.

With the European Champions Cup and Challenge Cup reportedly set to be suspended, the French government and Six Nations officials are expected to hold talks on Monday.

Yet Laporte does not believe there is any doubt that the competition, which starts in just four weeks' time, can be staged. 

He told RMC on Sunday: "It's a puzzle, but I think we should not be alarmed for the Six Nations tournament.

"The tournament will be played, with a health protocol dictated by the government, and linked to this mutant virus. Everything went well in the autumn [when the Autumn Nations Cup was staged], so will the upcoming Six Nations tournament, I'm no more worried than that."

The former Les Bleus coach added: "We have a meeting at the beginning of the week with the ministry of sports, a meeting also with the Six Nations Council.

"But we already talked to each other every day, and today there is no question of considering anything, except that we will play the tournament."

France are due to face Italy in the first game of the Six Nations at Stadio Olimpico on February 6.