BOSTON -- You could see the exact moment Boston Celtics guard Kyrie Irving realized what San Antonio Spurs guard Patty Mills was going to do.

It was in the first half of the Celtics' win over the Spurs on Monday, and Mills was dribbling above the 3-point line. He brought the ball through his legs once -- left to right -- then tried to go into an in-and-out dribble.

Irving's eyes flicked downward instantaneously. The in-and-out dribble is a move Irving has perfected, so it made sense that he anticipated it, and in perfect sequence -- as Mills tried to bring the ball across his body and start his drive -- Irving planted himself and stuck out a hand. He deflected the dribble, Mills fumbled it, and Irving took off the other direction. A huge dribble pushed him out ahead of Mills, and he swung the ball around in transition to avoid the defender for the layup.

Kyrie has the quick hands, playing good defense this year.... pic.twitter.com/ovDVUoIAiY — BBALLBREAKDOWN (@bballbreakdown) October 31, 2017

The play was indicative of Irving's early-season performance.

"He's playing both ends of the floor really well," Brad Stevens said. "When you're guarding all those high screens in the NBA, that's not easy. And he's doing a good job of knowing when to peel back and switch. He's doing a good job of chasing when he needs to chase, he stays in plays, he gets his hands on balls. He got a couple more balls tonight. I think we can continue to get better at finding him on offense and figuring what our spots are for him, but you can tell he's getting more comfortable every time he takes the floor."

The note about pick-and-roll defense is interesting. Irving has always been known as a defender who will die on screens, which hurts in a modern NBA where bigs often come well beyond the 3-point line to become an obstacle. Against the Spurs, the task was a little simpler -- San Antonio's starting guard is Dejounte Murray, whose effective field goal percentage is in the 14th percentile, per Cleaning The Glass. Against a poor shooter, Irving can simply slip under every screen and roam off the ball while recovering safely.

But Irving's rotations have been good, and as Stevens noted, the star guard has lightning quick hands -- a quality that may have been underrated when his defense was analyzed in Cleveland. But the biggest question about Irving's defense has always been less about whether he can and more about whether he will.

So far, he has. Irving credited Stevens for the improvements.

"(Stevens) does a great job of putting out a great game plan for us, and it's our job to perform at a very high level," Irving said. "He'll stay on us about it, and for me being at the top of the key handling most of those pick-and-rolls, and having guys come in and filter in and having to switch in groups, we just want to be able to utilize that on given possessions and consistently do it."

Meanwhile, Boston as a team continues to defend well, limiting an admittedly short-handed Spurs squad to just 94 points. Irving said the team is proving their prowess, although doing it on a nightly basis is key.

"We're proving it," Irving said. "We just have to consistently do it. That separates the good from the great teams. It's early in the season, but we have to consistently do it every day."

The same applies to Irving, of course, but the early returns have been encouraging for the Celtics.

"I think he's getting more comfortable, he's getting settled in, and you know it takes time to be where we want to be," Al Horford said. "But this was a huge step for us tonight."