It's the year of the underdog in the 2018 Telstra Premiership - or so it would seem. While 2017 grand final opponents Melbourne and North Queensland are struggling, the Warriors, Tigers, Knights and Titans all boast winning records after five rounds. Check out NRL.com expert Jamie Soward's views on all 16 teams in this week's Power Rankings.

1. New Zealand Warriors (last week: 2)

No-one expected them to be here, but they're going out and doing everything that's asked of them. Blake Green is the buy of the year, along with James Maloney. He really brings a calmness and steadiness and they're really working for each other. For the first time in five or six years they seem to have found a real nice balance between running hard and getting into a grind, and then playing that Globetrotter footy. The Warriors deserve their first week at No.1 in the Power Rankings.

2. St George Illawarra Dragons (1)

The Dragons drop down after a couple of weeks at No.1. I would've liked to see them go on and do a job in front of a big home crowd against Souths. Their attack is so exciting to watch and there's that expectation there, and this is the challenge for the top teams - their expectations meeting reality. They want to make the top four and now they're expected to after such a great start to the year. The Dragons were good on the weekend and Paul McGregor would've liked that match-up being so tight.

3. Wests Tigers (3)

Talk about being on the bus, talk about effort, talk about trust - this team is just all in when you look at what they're doing for each other, and how they've bought into the message Ivan Cleary is bringing. I can't wrap this team enough. If the two teams above them weren't undefeated I'd have the Tigers on top of the Power Rankings.

4. Penrith Panthers (5)

They only move up one spot. I thought the game against Parramatta was an opportunity to back up their massive road win against the Cowboys with a really efficient performance and come away with 16 to 20 points. I know it was against a desperate Parramatta side but it was a little bit stuttery, which was probably off the back of a long trip to North Queensland. They've started out with a 4-1 record so they're well placed at this stage of the season.

5. Sydney Roosters (6)

The Roosters still have some stuff to work on. Their attack was predictable at times but you still have to be able to stop it and they get it right more often than not. James Tedesco found some gaps, Luke Keary was outstanding and Cooper Cronk continues to show he's the best halfback in the game.

6. Melbourne Storm (4)

I'm giving the Storm one last week. Their attack doesn't look fluent at the moment. They're scratchy and clunky when they shift the ball. They're making some uncharacteristic errors. You don't often see what Josh Addo-Carr did last week in any game, let alone by a Melbourne player. I'm backing that they bunker down and bounce back against Newcastle. It'll be a tough game but they very rarely lose at home and almost never lose three in a row.

7. Newcastle Knights (10)

Kalyn Ponga put points on for them but I was more impressed with the way they hung in there defensively. They had the right to go on and win that game by 20 but sometimes it doesn't happen like that. They really held on and defended for each other when it got tight and came up with an important result at home.

8. Gold Coast Titans (11)

An outstanding win against Manly. They're won three out of five and they're really playing for each other. Ash Taylor and Kane Elgey have a nice combination developing. Kane Elgey has been a revelation the last two weeks and Titans fans will be wondering where this has been. Jai Arrow is a future Origin player.

9. South Sydney Rabbitohs (9)

The Rabbitohs keep hold of ninth spot in the Power Rankings based on their effort at a tough place to win like Kogarah, against a team that's playing very well. The first 60 minutes wasn't great but they hung in there and showed they can score some points when they play a bit more ad-lib. I think some second-phase footy is going to help the Rabbitohs, especially guys like Cody Walker and Greg Inglis.

10. North Queensland Cowboys (7)

The Cowboys have dropped out of the upper echelon of the Power Rankings for the first time. They don't look cohesive, they don't look excited. They look like they're playing with a lot of stress. The expectation that comes with adding Johnathan Thurston to last year's grand final team could be weighing down on them, but they just don't look like a happy team at the moment.

11. Cronulla Sharks (8)

The Sharks were disappointing against the Roosters. The Matt Moylan fullback experiment was great and I hope they stick with that. There's another piece to add to the puzzle with Josh Dugan coming back this week, but they're obviously still working some things out, even after six weeks of the competition.

12. Canberra Raiders (15)

This was the 2016 Raiders, the one we all thought was headed for big things. They were outstanding. They really competed hard and copped a lot of injuries, and it was just the sort of gutsy effort they needed. I think Aidan Sezer finally realised it's his team.

13. Manly Warringah Sea Eagles (12)

The Sea Eagles can't win away from home so I can't put them up there in the Power Rankings. They showed some signs in Gladstone but they didn't want it as much as the Titans. They really got out-enthused in some areas by a really energetic Titans side.

14. Brisbane Broncos (13)

I cannot get a read on the Broncos. They're a real Jekyll and Hyde team. They had five repeat sets in the first half and didn't score any points. Anthony Milford was great but Kodi Nikorima was quiet so they're still having some problems in regards to getting their attack right.

15. Parramatta Eels (16)

I know this will cause some controversy because they haven't won a game yet, but their effort was a lot better on the weekend, and sometimes you'll find in the Power Rankings that effort or how a team plays is going to reflect how they move up or down the rankings.

16. Canterbury Bulldogs (14)

The Bulldogs drop down this week. I saw some really bad signs in terms of their attack going backwards. Their effort probably wasn't there as much as it should've been. They had a lot of ball but they missed some really easy tackles which allowed the Raiders to build.