The matchups are set. All 16 seeds for the NBA playoffs tip-off on Saturday. Typically, the No. 1 and No. 2 seeds are safe. Since 2015, the No. 1 and No. 2 seeds have combined 48-11 record and advance to the second round.

What about everyone else? This is the time of years when the teams that caught fire during the final weeks of the season try to keep it going while other teams saved their best basketball for the postseason.

Looking at the playoff bracket, there are several playoff matchups that are intriguing with several teams that could be on upset alert.

Here is a look at the teams that could be on upset alert in the first round of the NBA Playoffs.

Philadelphia 76ers

|Charles Trainor, Jr./ Miami Herald|
Photo: Charles Trainor, Jr./ Miami Herald

For the first time since the 2011-12 season, the 76ers are back in the playoffs.

With the core of Ben Simmons, Joel Embiid and Robert Covington, Philadelphia won an impressive 52 games and earned the third seed in the NBA East. They are currently riding an NBA -best 16-game winning streak.

With that said, Philly is one of the younger teams in the NBA. Only Jerryd Bayless, Amir Johnson, J.J. Redick, Marco Belinelli and Ersan Ilyasova have playoff experience. Meanwhile, Philadelphia has 10 players with two years of experience of less.

Head coach Brett Brown has been in the playoffs before, as a assistant head coach to Gregg Popovich and San Antonio Spurs.

Philly tied the regular season series with the Miami Heat two games apiece.

Embiid could miss the beginning of the playoffs with an orbital fracture in his eye, that could hurt the '6ers right off the bat. Kelly Olynyk and Hassan Whiteside could take advantage of this and control the boards and control the tempo of the game for the Heat.

The veteran leadership of Goran Dragic, Dwayne Wade and Adonis Haslem could come into play for the Heat as they have had the taste of playoff experience with Wade and Haslem winning championships.

The depth and versatility of Miami could be the catalyst for an early playoff exit for Philly.

Boston Celtics

|Maddie Meyer/Getty Images North America|
Photo: Maddie Meyer/Getty Images North America

The Celtics (55-27) once again find themselves in the playoffs. Last season the Celtics were eliminated in the Eastern Conference Finals by the Cleveland Cavaliers. Meanwhile, the Milwaukee Bucks were eliminated in the first round by the Toronto Raptors.

Early in the season, Boston looked like a favorite to dethrone LeBron James and the Cavs and own the east. Their chances greatly improved when Boston traded for Kyrie Irving. However, per Adrian Wojnarowski, Irving will be out for the remainder of the season following left knee surgery. To add insult to injury, Gordon Hayward and Daniel Theis are also out for the remainder of the season.

The Bucks won five of their last eight games coming into the post season. The two teams won two games apiece during the regular season.

Giannis Antetokounmpo will look to dominate the floor against the Celtics. If he plays like he is the best player on the floor, Antetokounmpo is nearly unstoppable.

Malcolm Brogdon, Eric Bledsoe, Jabari Parker and Khris Middleton will look to keep Boston off balance during the series as well.

With several weapons out for Boston, they could be in trouble when the Milwaukee comes into town.

Oklahoma City Thunder

For the second season in a row, the Utah Jazz will play in the postseason. For OKC this is their seventh trip to the playoffs in the last eight seasons. What makes this first round matchup one to watch is that there is no clear underdog.

Yes, Oklahoma City won the season series three games to one. Yes, the Thunder have more "stars" on the roster. Yes, OKC has more playoff experience. But, Utah is coming in as one of the hottest teams in the league.

The starting lineup for the Jazz matches up real well against the Thunder lineup.

Rudy Gobert and Donovan Mitchell will give the the Thunder a lot of problems. ​Jae Crowder, Dante Exum and Ekpe Udoh will be the forces coming of the bench of Utah.

If Russell Westbrook, Paul George and or Carmelo Anthony can't get it going, it could another early exit for the Thunder.

Golden State Warriors

|Ronald Cortes/Getty Images North America|
Photo: Ronald Cortes/Getty Images North America

For the first time in quite some time, the Golden State Warriors are vulnerable in the first round.

Both Stephen Curry and Patrick McCaw are likely to miss the entire first-round series. Even without Curry, Shaun Livingston, Klay Thompson, Kevin Durant and Draymond Green will look to lead the Warriors into the second round.

During the regular season, Golden State took the season series three games to one against San Antonio. Golden State averaged 104.8 points per game against San Antonio, with the Spurs averaging 98.3.

Patty Mills, Danny Green, Rudy Gay and LaMarcus Aldridge will have to go all out against the Warriors if they want to earn a spot in the second round.

The two biggest factors will be Gregg Popovich and Kawhi Leonard. Coach Pop coached the Spurs to 47 wins this season. If Coach Pop can out coach Steve Kurr and company, it could be a long series for the Warriors.

As far as Leonard goes, he and the Spurs need to get him on the floor as soon as possible. With Kawhi, San Antonio is a real problem. Without him, the Spurs are missing one of the best two way players in the league.