(CNN) -- Luis Suarez illustrated why he is one of the world's most controversial soccer players on Sunday as he bit an opponent before going on to save his club from defeat with a last-gasp goal.
The Liverpool star showed his best and worst sides in a controversial 2-2 draw with Chelsea, and he potentially faces another long suspension after his assault on Branislav Ivanovic.
Suarez, the English Premier League's top scorer, wrestled with the Chelsea defender and then clearly sank his teeth into the Serbian's arm.
The incident was not seen by referee Kevin Friend, who shrugged off Ivanovic's angry protestations. Suarez later apologized on his Twitter account.
"I'm sad for what happened this afternoon, I apologize Ivanovic and all football world for my inexcusable behavior. I'm so sorry about it!!" wrote Suarez. Among his Twitter followers is former boxing champion Mike Tyson, who infamously bit off part of an opponent's ear in 1997.
It is not the first time Suarez has bitten an opponent -- he was suspended for seven matches in late 2010 after an incident while playing for Dutch club Ajax, two months before joining Liverpool.
He was also banned for eight matches after racially abusing Manchester United's Patrice Evra in October 2011, and former Liverpool captain Graeme Souness said after the Chelsea match that the 26-year-old is in "last-chance saloon."
Souness, one of the match analysts for UK broadcaster Sky Sports, said the club needed to take strong action after an incident which reflects badly on one of the world's most famous teams.
"People will be talking about this for a long, long time and it's going to show Liverpool in a very bad light -- especially in this week of all weeks, the anniversary of Hillsborough," said the 59-year-old, referring to the 24th anniversary of the stadium tragedy where 96 people died after a crush during a match between Liverpool and Nottingham Forest.
"It can't happen again. I firmly believe this puts him in the last-chance saloon as a Liverpool player -- the board have to see it that way because they're risking everything this great football club stands for," added Souness, who was a player during Liverpool's glory days of the 1970s and '80s and later managed the club.
Liverpool's current manager Brendan Rodgers refused to criticize Suarez in his postmatch interview with Sky, saying he had yet to see the incident and that he would review it later.
"I'll make an honest appraisal on it and comment afterwards. It's not for me to make any rash comments or predictions now," said Rodgers, who claimed Chelsea's former Liverpool striker Fernando Torres had elbowed his defender Jamie Carragher in the face. The Spaniard was booked for that challenge.
Rodgers later added on Liverpool's website: "Having reviewed the video footage and spoken to Luis, his behavior is unacceptable and I have made him aware of this."
Rodgers' predecessor Kenny Dalglish was widely criticized for publicly defending Suarez during the Evra case, and after the punishment was handed out by the FA.
Another former Liverpool player, Jamie Redknapp, said that the actions of Suarez -- who has often been criticized for diving on the pitch -- were "indefensible."
"There is that madness-genius gene in him because as a player he's exceptional, with people talking about him being player of the year, but what he did today, is indefensible," said Redknapp, also a Sky analyst.
"Even the staunchest Liverpool supporters cannot look at that and think that's alright.
"Why on earth would you want to take a chunk out of someone's arm when you are on a football field? That is an absolutely incredible act of brutality. It's madness."
Liverpool, owned by the U.S. Fenway Sports Group, insisted it would take internal action against Suarez.
"His behavior is not befitting of any player wearing a Liverpool shirt and Luis is aware that he has let himself and everyone associated with the club down," said managing director Ian Ayre.
"We will deal with the matter internally and await any action from the FA."
The incident overshadowed former Liverpool manager Rafael Benitez's return to Anfield with Chelsea, but the Spaniard refused to comment on Suarez -- instead complaining about the near seven minutes of time added on that allowed the striker to head an equalizer for his 23rd EPL goal of the season.
"Six minutes and 45 seconds is difficult to explain. We need to analyze why we didn't stop the cross and they scored, but in the normal circumstances we would have finished the game," Benitez said.
Suarez had earlier set up second-half substitute Daniel Sturridge to make it 1-1 after Oscar's first-half headed opener, but then inexplicably handled the ball in his own penalty area to allow Eden Hazard to put Chelsea in front again from the spot.
The draw dented Chelsea's chances of qualifying for next season's European Champions League, leaving Benitez's team in fourth place -- a point behind Arsenal and one ahead of Tottenham.
Tottenham had earlier stunned second-placed Manchester City 3-1, a result that means Manchester United can wrap up a record-extending 20th English title with four matches to spare.
Victory in Monday's home match against relegation-threatened Aston Villa will end City's Premier League reign, as manager Roberto Mancini ponders what has gone wrong this season.
"I can't believe that we lost this game because we played very, very well for 80 minutes," the Italian manager said after Spurs came from behind to score three late goals.
"This is our problem this year, when we have chances we don't score."
Samir Nasri gave City the lead in the fifth minute, but Gareth Bale set up Clint Dempsey's equalizer with 15 minutes to play before substitute Jermain Defoe cut inside visiting captain Vincent Kompany and lashed in a right-foot shot.
Bale, returning after an ankle injury, then wrapped up the win with his 18th league goal this season.
City's only hope of silverware this season is the FA Cup, with the final against Wigan on May 11 as Mancini seeks to win back the trophy he lifted two seasons ago.
"We needed to win because we want to get second position and to have a better life for the next week, but we didn't deserve to lose -- we deserved to win," he said.
"The championship was finished three or four weeks ago, they deserved to win it. I think that it's important for us to win as many games now as we can."