Dallas certainly had Boston rattled in the opening exchanges and took a 10-point lead going into half-time.
They rallied back to record a 97-90 win with Irving top scoring again with 23 points.
But he found it tough to cope with rookie Smith Jr, who caused Boston all sorts of problems in the opening quarter.
The young point guard was clearly fired up for his match-up against Irving and things boiled over when Irving and his opposite number got into each other’s faces before being separated.
But Irving was keen to downplay the incident as nothing more than two competitive guys coming to blows on the court.
“It’s the beautiful part,” Irving said.
“When you get matched up it’s always an exciting match-up.
“It’s a unique opportunity to play against some of the best point guards and I struggled against Smith.
“He’s veteran-savvy. In order to try and take you out of the game.
“Mix-ups in the game – that’s always a part of it. People bumping and trying to prove something that’s always fun but it stays within the game.”