Just four weeks into the NBA season and we've already witnessed some surprising performances, with some teams exceeding expectations while others falter under the pressure.

Here is Zero US Sports' top five most surprising teams to start the NBA season:

5. Charlotte Hornets

After losing one of the greatest players in the franchise's history, you would be forgiven for thinking the Charlotte Hornets would be staring down the bottom end of the Eastern Conference. While the Hornets haven't blown anyone away, sitting at a modest 6-7, the fact they haven't completely capitulated without Walker as expected is surprising to say the least.

Charlotte are unlikely to make the post-season, but the development of guard Devonte' Graham and forward PJ Washington will delight fans who had little to smile about heading into the season. The franchise have also managed to beat the likes of Indiana and Sacramento without injured veteran Nicolas Batum.

4. Miami Heat

The Heat are currently tied for second in the East and look almost unbeatable at the American Airlines Arena. After finishing 10th in the East last season, Miami, led by new recruit Jimmy Butler and rookie Kendrick Nunn, have taken down Houston and Milwaukee, marching to a 9-3 record.

Butler leads the franchise in scoring, with 19.4 points per game, while Nunn is second amongst rookies, with 16.9, trailing only Ja Morant. Bam Adebayo has also impressed for Erik Spoelstra's team, with the power forward averaging 9.8 rebounds and 1.4 blocks per game. The December 5 matchup against the 8-1 Celtics will certainly be one to watch.

3. Phoenix Suns

Over to the West now and perennial strugglers the Phoenix Suns seem to finally have things figured out. On to their fifth head coach in four seasons, the Monty Williams-led Suns are sitting in the fifth seed in the Western Conference and playing an exciting brand of basketball.

Superstar Devin Booker is finally getting the support he needs with Ricky Rubio averaging  8.8 assists per game and even Aaron Baynes getting involved in the action with 16.2. Phoenix have impressed through upset wins against the Clippers and the 76ers and Booker has dropped 30+ on three occasions, stirring up All Star talk already.

2. New Orleans Pelicans

Following a dream off-season, where they secured the number one pick and Zion Williamson, alongside a bevy of young talent in exchange for the want-away Anthony Davis. However, at 4-9 its clear it hasn't gone to plan for Alvin Gentry's men. Williamson has had surgery on his knee, while Lonzo Ball and Jrue Holiday are also struggling with injury.

The Pelicans weren't expected to contend but they certainly weren't expected to flop either. One shining light for the franchise has been the explosion from Brandon Ingram, the former Laker is averaging almost 26 points per game and has saved the team from being embarrassed on multiple occasions.

1. Golden State Warriors

The Warriors went 73-9 without Kevin Durant in 2015-16 and while they're not the same side they were back then, nobody could've predicted their sharp decline in 2019. The free agent signing of D'Angelo Russell was seen to be a solid replacement for the injured Klay Thompson but it has quickly turned into a nightmare with Russell boasting a +/- of -10.5.

The bad news doesn't end there for Golden State, who are dead-last in the West with just two wins from 12 games. Stephen Curry, who has already struggled for form early in the season, has suffered a broken hand and isn't expect to return before Christmas. Steve Kerr is now relying on the likes of Eric Paschall and Alec Burks to save the season until Curry gets back or gets put on ice and the team opt to tank.