The astonishing incident, the latest to blight Chelsea's season, happened with just over 10 minutes remaining of the tie, which the Blues lost 2-0 on aggregate. The game was goalless on the night and Hazard lost patience when the ball boy refused to hand over the ball after it had gone out of play for a goal-kick.
The ball boy fell to the ground as Hazard attempted to get the ball from him with the Blues forward then trying to kick it from under him but instead he appeared to make contact with the youngster. Several Chelsea players went to tend to the ball boy, who was left holding his ribs, before referee Chris Foy produced a red card.
The ball boy was quickly ushered away from the tunnel area after the final whistle having been interviewed by police officers. A Swansea spokesman confirmed no action would be taken, and that Chelsea had invited the 17-year-old, who has been a ball boy at the Liberty Stadium for six years, into their dressing room.
He said: "The police have interviewed the boy and his father and there are no charges going to be pressed, as far as they are concerned that is the matter closed. The ball boy has been into the Chelsea dressing room after the game and shaken hands with Eden Hazard. The likes of John Terry and Frank Lampard were exemplary in their behaviour in welcoming him into the dressing room.
"Chelsea asked if he could come in and our kit lady took him in and they shook hands, he is fine. As far as we are concerned the matter is closed. He has been a ball boy here for six years with no incidents here at the stadium."
Chelsea manager Rafael Benitez said that Hazard's actions would be dealt with internally by the club, but it is another blow to the London club's reputation in a season already including the John Terry racism scandal, the Mark Clattenburg affair and the unpopular sacking of Roberto Di Matteo.
He said: "The ball boy has been in the dressing room talking with Hazard and they have apologised to each other. They know they were wrong, that's it. He was wasting time, Hazard was frustrated, he wanted to get the ball back quickly so they have both made a mistake and we cannot say too much. We will deal with this internally. We will analyse and wait to see if there is any action from the FA."
But Benitez reacted angrily when he was accused of attempting to condone Hazard's actions.
"I do not know what you expect from me," he said. "Do you think we are not disappointed with the situation, that we do not regret what happened? Do you think they have not apologised? They have done it so what can we do now? Do you want to change things? We cannot. The player spoke to the boy and he said sorry because it was a mistake so what else would you expect?"