Zlatan Ibrahimovic and Romelu Lukaku were involved in a very heated clash during Tuesday night's Milan derby.Both players fired obscenities at one another late in the first half and they were duly booked by the referee for their actions.The incident started after AC Milan defender Alessio Romagnoli committed a cynical foul on Lukaku, one which the Belgian was far from happy with.Zlatan and Lukaku then butted heads after the Swede stepped in, before exchanging personal insults once they'd been separated by their teammates.The argument between the pair - who played together at Manchester United - continued after the half-time whistle was blown.It was quite a surprise the two didn't eventually come to blows, that's how intense their feud was during the Coppa Italia quarter-final at San Siro.Due to the fact they played together at United, there's quite a bit of history between Zlatan and Lukaku.Back in 2017, the former was full of praise for the latter, stating in an interview that the Belgian striker had "made his job easier".

Zlatan's interview

"The team is stronger this season," the Swede said. "Lukaku is in the team scoring a lot of goals, and he is making the job easier for me, because last year when we were playing we could not change that role.

"We had one scoring the goals, and doing that job, and there was no variations for the coach. This season it is easier. Lukaku is only positive, because he makes my 'comeback' less pressured, it gives me a lot of time, and I'm happy for that.

"The more time I get, the better it gets. He's scoring his goals and doing what he needs to do. When I come back, the coach is there, we will see how things go. I see it very strong. Because the more quality we have in the team, the more alternatives we have, the easier it is for the manager."

Ironic, eh? Lukaku certainly didn't make his job easier on Tuesday night, but the Belgian has spoke highly of Zlatan in the past as well.

“I recognize myself in Zlatan," he said around a year ago, per Kristof Terreur. "We understand each other. Few people know it, but he helped me a lot at the time. He is a champion. And, as we say, he has the mentality of a dog. He never gives up. I still take his advice with me."

It's a shame those past kind words from the pair were completely forgotten about at San Siro during what was a quite epic game.

Zlatan opened the scoring on the night, but was sent off early in the second half and Inter capitalised on his lack of discipline.

Lukaku equalised from the penalty spot in the 70th minute, before Christian Eriksen won the game with a stunning free-kick in stoppage time.