More than 100 people were arrested, mainly for drink-related offences, as trouble spiralled after the match.
Referee Hugh Dallas needed stitches after being hit by a missile from the crowd and a Celtic fan was taken to hospital after falling from the upper tier of the stand.
4. Ronda Rousey vs Bethe Correia
Earlier this month, Rousey KO-ed Correia in a spectacular bout lasting less than a minute at the UFC 190. Her decisive victory followed deliberate baiting by Correia pre-match, when she said she hoped Rousey wouldn't commit suicide after getting beaten for the title. Rousey's father committed suicide when she was a child, something Correia claims she didn't know.
After the win, Rousey can be seen saying "don't cry" to Correia as she lies unconscious on the mat. "I said the exact same thing she was saying to me at weigh-ins," Rousey explained later. "She was screaming in my face at weigh-ins, she was saying, 'Don't cry.'"
3. Quade Cooper vs Richie McCaw's head/ the New Zealand public
Ok so maybe this one isn't technically a feud, considering good-guy McCaw refuses to join in slagging Cooper off, but New Zealand sports fans have made it clear they'll neither forgive or forget Cooper's knee-to-head or his perceived arrogance during the 2011 Rugby World Cup. For his part, Cooper didn't seem fussed about making amends - when asked about being branded public enemy number one he replied "to be honest, I don't really care."
2. Grant Dalton vs Russell Coutts
Dalton's feud with Montgomery isn't his only soured yachting relationship. In 2013 Coutts implied he thought Dalton was too old to be on board during an America's Cup race and mocked Dalton's sailing record. "Grant is racing on the boat. He's 54 years old ... there's nobody in New Zealand he can find that's better than a 54-year-old," he said, before getting in a backhanded compliment about Dalton's ability to fundraise despite only having "a lot of second place wins." Dalton shot back with barbs about Coutts' defection to the US and Switzerland, a sore point for many New Zealand yachting fans.
1. Tonya Harding vs Nancy Kerrigan
No sports feud top five would be complete without the mention of the infamous "skategate" of 1994. Dubbed "the whack heard around the world," America's sweetheart skater Kerrigan was hit in the knees with a lead pipe while training for the US skating championships, leaving her unable to compete. This allowed her biggest rival, Harding, to skate to victory.
As the pair prepared for the 1994 Winter Olympics, rumour started circulating that Harding had something to do with the attack on Kerrigan. Eventually it was revealed Harding's husband, Jeff Gillooly, was behind the attack. Harding denied she knew about it beforehand, but was eventually convicted of conspiracy.
