Robin Lopez's face lights up and he looks like a very big kid on Christmas Day when he's talking about comic books or movies. But when the conversations turn to basketball and defense, Lopez's face hardens. There's not a trace of a smile.

Lopez takes his role as a selfless, physical basketball player seriously. He plays with passion, intensity and energy, and sometimes he can be too emotional when a call doesn't go his way or an opponent scores on him.

But these are many of the things the Knicks were drawn to when they decided to give the 7-foot center $54 million over four years to anchor their defense and bolster their rebuilding effort.

"It's something I totally embrace," Lopez said. "I think I'm a lot prouder of them wanting to sign me for reasons -- they wanted to build, they wanted to have good character guys, hard-working guys, they wanted to build the right kind of atmosphere for the team. I'm so proud to be a part of that.

"If you look around the gym, you got a lot of great guys, a lot of chemistry and a fantastic foundation."

Lopez, who will open the regular season Wednesday night in Milwaukee as the Knicks' starting center, was the franchise's "big" free-agent pickup.

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He's known more for his wild mop of hair, similar to Sideshow Bob from the Simpsons, and for his fights with NBA mascots. But the Knicks made the twin brother of Nets center Brook Lopez the centerpiece of their summer free-agent spending.

Lopez isn't a sexy name like former Portland teammate LaMarcus Aldridge, who signed with the Spurs, the Grizzlies' Marc Gasol, the Clippers' DeAndre Jordan or even Greg Monroe, the player the Knicks were linked to most until he chose the Bucks.

Team president Phil Jackson said Lopez was a better fit than Monroe because he's bigger and a better defender and because his presence gives the Knicks the flexibility to use Carmelo Anthony at power forward.

Team-first guysJackson locked up Lopez, Arron Afflalo, Derrick Williams and Kyle O'Quinn in a matter of days and added Sasha Vujacic and Kevin Seraphin later in the summer.

The Knicks believe they've assembled a more team-oriented group than last season's 17-win squad and certainly a better defensive club, in large part because of Lopez.

"Well, his hair alone will change a lot of shots," Derek Fisher said. "He has a presence. He commands things from his teammates. He's a vocal guy. He's not afraid to make sure guys are doing their job. When we have an anchor on the defensive end who's really communicating and letting guys know what they should be doing and what's going on out there, that helps.

"He's a big dude. So it's not as easy when he's around the rim to go and finish. I think he's going to help us in a big way in terms of being a guy people have to think about when they go in the lane."

Lopez's hair jumps out at you more than his stats. He has career averages of 8.2 points, 5.0 rebounds and 1.18 blocks in seven NBA seasons with Phoenix, New Orleans and Portland.

Lopez has averaged more than eight rebounds only once. He ranked 25th among centers last season with 6.7 rebounds per game. Only three times has he blocked more than one shot per game. Lopez's high came two seasons ago for Portland when he rejected 1.7 shots per game, fifth among centers.

But he guards the pick-and-roll well and is a good team defender, and his teammates appreciate what he does for them.

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"I love him," said Afflalo, who played 25 games with the Trail Blazers last season. "He's a big inside presence. He's unselfish with the way he plays the game. He's one of the best vertical, shot-blocker, defender-type players and he's a good teammate."

If Lopez can make one of the Knicks' biggest weaknesses last season a strength, the club might have his twin brother to thank. Brook Lopez was always more skilled offensively. Their battles on the court led to some "epic fights" -- and to Robin Lopez focusing on defense.

"Brook's always had a knack for putting the ball in the bucket, and I would have to go out there and try to stop him," Robin Lopez said. "That would be my thing. I don't like being scored on on the floor. It's as simple as that."

Comic relief

Robin and Brook are both into comics and work on graphic novels together. Brook is the writer and Robin the artist.

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Robin dressed as "Doc Brown" from "Back to the Future" earlier this month for New York's Comic Con at the Javits Center. On Friday, he dressed as Thor and a group of kids were the rest of the Avengers. He read a comic book to them at the top of the Empire State Building.

He looks more comfortable in that environment than on the court. He was asked as an artist how he would depict himself as a basketball player, and had to give it some thought.

"It definitely would be something very dynamic," Lopez said. "It might just be a portrait, a close-up, some kind of expression on the defensive end."

Lopez doesn't have much of an offensive game. He's a good passer and screen-setter and opens up the floor for his teammates. He also is one of the NBA's best offensive rebounders. He set the Trail Blazers' single-season record for offensive boards two years ago (326).

He doesn't do quite as well on the defensive boards. Lopez said he boxes out his man and lets his teammates get the rebound on defense. But on offense he's trying to get his team another possession.

Lopez said he always has cared about helping his teammates rather than stuffing his own stats. That became even more of a priority when Lopez began his career in Phoenix and called Steve Nash, one of the most selfless players ever, his teammate.

"When you have somebody out there that's willing to work for the team first, that's contagious," Lopez said. "In Phoenix, I learned that from Steve Nash, Grant Hill, so many different guys. When you're playing with somebody like Steve, like Grant, that just passes on to you.

"It definitely brought that to the forefront for me. I'm glad that's where I spent my formative NBA years because I kind of learned to play the right way."

The Knicks believe they'll be the beneficiaries of that on both ends of the court.