The Sixers kick off their postseason run on Monday against their old rival the Boston Celtics. Here are some things to keep an eye on before the action tips off at 6:30. 

Defensive Matchups 

These two teams run almost completely different types of lineups. There are the Sixers who run a two big man lineup with Joel Embiid and Al Horford, and then there are the Celtics who run a lineup full of wing players in Jayson Tatum, Jaylen Brown, and Gordon Hayward. How these two teams matchup defensively is a key thing to watch. 

Brett Brown told the media yesterday that the idea of starting rookie Matisse Thybulle has been talked about, but no decision has been made. It will be interesting to see how the Sixers defend if they keep Horford in the starting lineup.

Horford has had his struggles defending on the perimeter and it will be tough for him to chase around one of the Celtics' wing players. On the same not it will be interesting to see how Celtics' coach Brad Stevens attempts to combat the size of the Sixers' lineup. 

Embiid adjusting to double teams 

It is no secret that Joel Embiid will see a double team almost every time down the floor. Brad Stevens is going to make it as hard as he can for Embiid to get going. With that being said, how Embiid operates against the double team will be a big tell of how the game will go for the Sixers. 

Embiid showed in the seeding games that he has improved his game passing out of double teams. Brett Brown has even praised Embiid's "quarterbacking" when faced with multiple defenders. If the Sixers are going to pull it out in this series we need to see a composed Embiid around the rim. 

Turnovers are something the Sixers need to limit, they have been careless with the ball in the past, and against a team like Boston, you cannot waste possessions. Embiid is going to have to be strong with the basketball and be able to find shooters and cutters out of doubles. 

Containing Jayson Tatum 

In the seeding games, we saw scorers go off for big performances on the Sixers. The loss of Ben Simmons leaves a big hole for the Sixers defensively, and it might become apparent very fast in this series. 

Jayson Tatum is a good offensive talent and can run up his scoring numbers if he gets going. Containing him in this series needs to be a major focus for the Sixers if they want to win. Guys like Matisse Thybulle and Josh Richardson are going to have to bring the energy on defense as they will likely be the primary defenders on Tatum. 

Keeping Tatum off balance and throwing him different looks will be crucial. If they allow him to get into a rhythm and get easy shots they will be in trouble. We saw in the first seeding game when TJ Warren went for a career-high on the Sixers. Brett Brown is going to have to adjust in-game on Tatum to make sure he doesn't go off for a big scoring night. 

Kevin McCormick is the 76ers insider for 97.3 ESPN and 76ers editor for Sportstalkphilly.com. Follow him on Twitter @KevinMcC973.