BOSTON - When it comes to stopping Knicks rookie sensation Kristaps Porzingis, there are no easy answers.

A 7-foot-3 power forward who can hit from three-point range is about as rare as it comes, and it's taken some time for teams to figure out how to guard him.

But it can be done, and the Celtics have proven that.

Porzingis did score 26 points against the Celtics back on Jan. 12, and hasn't scored that many points since, but he was held to just six points in the second half of that game after Brad Stevens stuck Marcus Smart - a stocky 6-foot-4 guard - on him.

The Knicks still managed to pull that game off, 120-114, their only win against the Celtics this season.

When the two teams met again on Feb. 2, Porzingis was held to just 10 points and five rebounds in a Celtics 97-89 win.

"I think the last couple of times we've played him, I think Amir, we even put a couple smaller guys on him, did a great job of just being physical with him," Jared Sullinger said. "Just understand that if he makes a tough shot, he makes a tough shot. I think day in and day out we try to make the go-to players their shots as tough as possible."

Porzingis is averaging 14.0 points, 7.4 rebounds, 2.0 blocks per game this season. But everybody knows he's still not the go-to guy on the team. That title falls on Carmelo Anthony, who's averaging 21.5 points and 8.0 rebounds for the Knicks this season.

Anthony, however, hasn't had scoring nights over the teams' last two games. He scored 17 points on Jan. 12 and 16 points on Feb. 2, though he also grabbed 14 rebounds.

Limiting Porzingis and Anthony will be instrumental to the Celtics' chances on Sunday, but the Celtics can't ignore some of the other Knicks players like Aaron Afflalo. Afflalo was a big part of the Knicks' only win against the Celtics this season, scoring 24 points on 9-for-17 shooting.

"I think that obviously that whole thing starts with Porzingis and Anthony but they've got a number of guys who've hurt us in the games that we've played and [Robin] Lopez and Afflalo are at the top of that list as well," Stevens said. "So they've got a lot of good players. Porzingis is just a problem because a little bit like Kelly [Olynyk] for us, his ability to stretch the floor just puts you in a bind because it's hard to switch screens with a 7-foot-2 guy. He's a good player. We're going to have our hands full. They've been three close games that we played against them."

Here are some other factors that could play into Friday's game as the Celtics look to go 5-0 on their homestand and post their 13th consecutive home victory.

Good luck, Isaiah
If there's one thing we know about Isaiah Thomas, it's that he has a knack for driving to the lane and somehow figuring out a way to get the ball in the basket. Well, he's going to have a tough time against the Knicks. They average 5.6 blocks per game, ranking them 9th in the NBA. And if we all recall in the game back on Jan. 12, Thomas was blacked by Robin Lopez at the rim down three points with just over 20 seconds to play.

Steal this one
You wouldn't look at the Knicks and call them very "active" on defense. In fact, they rank dead last in steals per game with just 5.8. The Celtics, meanwhile, get their hands on a lot of balls. They come into Friday's game ranked 2nd in the NBA in steels per game with 9.5.

But here's a little twist: The Knicks protect the ball pretty well. Their 13.4 turnovers per game is the 8th fewest in the NBA.

Melo in Boston
Everybody knows that Carmelo Anthony's future in New York City could be up in the air. With the state of the Knicks, he may want out this summer - and the Knicks may want him out. The question is: Would the Celtics want him? It's hard to say. Melo is quite the polarizing player on the court. He'd certainly change the dynamic of this Celtics team and who knows if it would be for the better (Melo's history doesn't exactly show that it would be). But some people are calling for a superstar - he is one.

It will be interesting to see how the fans treat him on Friday night, and if he'll answer to any questions regarding a possible future in Boston.