Liverpool striker Luis Suarez has been banned for 10 games by the Football Association for biting Chelsea's Branislav Ivanovic.
The incident happened during Sunday's 2-2 draw between the sides.
The 26-year-old later apologised for biting the Chelsea defender and was fined by Liverpool on Monday.
The club, who have until Friday at 12:00 BST to appeal, said they were "shocked and disappointed" at the length of the suspension.
Uruguay international Suarez had accepted the FA charge of violent conduct but claimed his ban should be three games, the standard punishment for violent conduct.
The ban covers their final four games of this season and the first six games of 2013-14 - which could mean Suarez not playing again until late September or even October.
An FA statement read: "A three-person independent regulatory commission today upheld the FA's claim that a suspension of three matches was clearly insufficient and the player will serve a further seven first-team matches in addition to the standard three. The suspension begins with immediate effect.
"The Liverpool forward had accepted a charge of violent conduct but had denied the FA's claim that the standard three-match sanction was insufficient for the offence.
"The incident was not seen by the match officials and has therefore been retrospectively reviewed.
"Suarez has until midday on Friday 26 April to appeal [against] the additional suspension, above the standard three matches."
Reds managing director Ian Ayre said: "Both the club and player are shocked and disappointed at the severity of today's independent regulatory commission decision.
"We await the written reasons tomorrow before making any further comment."
It is not the first time Suarez has been charged with such an offence. He was banned for seven games when he was at Ajax after biting PSV Eindhoven midfielder Otman Bakkal's shoulder during a match in November 2010.
During his time at Liverpool, he has also received an eight-match ban and £40,000 fine by the FA for racially abusing Manchester United left-back Patrice Evra in December 2011.
BBC football pundit Mark Lawrenson, a former Reds defender, told BBC Radio 5 live: "I think they will appeal and might get it to eight. He's now becoming a constant offender. There's probably a sheet of A4 paper with all his offences over his career.
"He needs to learn quickly. It's distracting for everyone. Even if it gets reduced to eight, that's 20% of the season. Liverpool are going to have to make a decision on his future.
"He and Ivanovic had a few niggles before the incident but nothing really seriously untoward. Jamie Carragher and Steven Gerrard said maybe he needs some help - he obviously does. At the moment it's to the detriment of the football club. You wonder what he will do next.
"It [Suarez leaving Liverpool] is a possibility. But any business where you have an asset worth £30m or £40m, nobody is going to sack him."
Suarez is on the six-man shortlist for the Professional Footballers' Association player of the year award and PFA chief executive Gordon Taylor earlier said: "It would be embarrassing if he is named player of the year.
"But we have got to deal with it and make sure he is player of the year not just in a footballing sense but as a human being as well and we will be trying to do that."
Liverpool Supporters Club chairman Richard Pedder said: "I don't think it's a shock, I think he deserves everything he gets.
"It's down to the club to tell him 'this is your last chance'. He won't leave the club [this summer]. They shouldn't have said anything and just accepted the ban.
"With them releasing a statement, it's going to go on and on again and we want it closed. We haven't had enough but we're concerned. Nobody is bigger than the club."
Former Liverpool striker John Aldridge said: "It's a massive, massive hit for both the player and the club.
"But he has to control it, for the sake of himself and Liverpool Football Club, he can not let anything go wrong on the pitch again."
Former FA chief executive Mark Pallios said: "They do have the latitude in their regulations to do this. Tomorrow we will see in the written reasons the weighting they have given to the image of the game and his previous record.
"It's a strong statement from the FA. Biting has no part of the game but tackling does. You expect to get tackled and that's more subjective."
Match of the Day host Gary Lineker said on Twitter: "Very strong punishment. Vital now that FA are consistently strong on all issues eg racism, abusing refs etc. Also this ridiculous nonsense of 'if the ref saw it they can't punish retrospectively' has to be addressed!"
Former FA compliance officer Graham Bean thinks Suarez's claim that a three-game ban would be the right punishment could have been behind the length of the suspension: "I expected it to be seven or eight. He challenged the FA with a ridiculous assumption that three games was sufficient and that may have backfired on him. There is a degree of window dressing, the FA trying to send a message out as a PR exercise."