In the quarter-final round, Milan crashed out of the Coppa Italia after losing 2-1 to Inter at San Siro on Tuesday night.
In the 31st minute, Ibrahimovic created a trademark finish to open the scoring, but after a tense exchange with Lukaku, who responded aggressively to a foul from Alessio Romagnoli, he was given a yellow card just before the interval.
The 39-year-old squared up to his Inter counterpart and their respective team-mates had to drive the pair apart, but they proceeded to hurl insults at each other as the teams at half-time made their way down the tunnel.
“At one point, Lukaku was heard saying to Ibrahimovic as tempers flared, “Well, let’s go inside you b*tch!” and he also accused the veteran frontman of insulting his mother.
Early in the second half, Milan had been reduced to 10 men when Ibrahimovic was involved in another controversial incident.
After tripping Aleksandar Kolarov in the middle of the pitch, Ibrahimovic was handed a second yellow card, leaving the Rossoneri with a mountain to climb to hold on and qualify for the semi-finals.
When Lukaku dispatched a penalty in the 71st minute, their stubborn resistance was finally over, and substitute Christian Eriksen scored a superb late free-kick to secure a famous Inter victory in stoppage time.
In his post-match interview, Pioli discussed Ibrahimovic’s ill-discipline, telling Rai Sport: “It influenced the sending off because he was booked there. I don’t know what they were saying. It can happen, we need to think about the next one.”
His urge to track back and support the team stemmed from the second yellow card. He may be slowing down, but it happens.
“In the dressing room, he apologized.”