Looking forward to Friday night's game, Dragons skipper Coombs said, "We are sitting sixth in the league and it's not something that we have achieved for a number of years. It's been a fantastic start but it's all about keeping it going.
"The Ospreys are going to be hurting a lot after their losses, including two Heineken cup games, but it's going to be a difficult evening for us. I am sure if we start as we started against Scarlets, full of confidence and ambition to run the ball, we just need to go there and challenge them.
"Whenever you play the Ospreys it's always going to be difficult because of the quality of players they have. They know how to turn things around they have been in this position before and they have come through it before. No doubt on Friday night they are going to be on fire and it's just important that we are on top of our game to win that match."
Dragons Director of Rugby Lyn Jones has made seven changes to his RaboDirect team, from the clash against Bath Rugby in the Amlin.
He makes only one change in the back three as Tom Prydie steps in on the wing while the centre pairing takes on a slightly different look with Lewis Robling who makes his first start of the season for the Dragons.
Italy fly half Kris Burton gets his third start of the season in the number 10 jersey to join Richie Rees who retains his scrum half place from last week.
There is only one change in the front row as young gun Sam Parry steps in at hooker and Hugh Gustafson moves to the bench. Matthew Screech also keeps his place alongside skipper Coombs in the second row. There is only one change in the back row with Jevon Groves moving into the flanker position, alongside Lewis Evans and Toby Faletau.
Opsreys Head Coach Steve Tandy is determined his side will bounce back from their defeat to Northmapton Saints in the Heineken Cup last weekend.
He said: "Obviously we are disappointed about Sunday but a game like this one is the perfect way for us to pick ourselves up and go again. This group has plenty of fight and spirit and are determined to do themselves justice, starting on Friday night.
"This is an important time of the season for us, one where we have traditionally done well when the core group and the spirit they have pulls us through. It won't be any different this season. There'll be boys coming into the 23 who will see it as a real opportunity to stake a claim for a regular place and we'll be encouraging that attitude as it will help to drive this squad on.
"It's a Welsh derby so that gives the game a bit of something extra. We've started the PRO12 well and with three of the next four games in the competition at home it's important that we make that count. Hopefully we'll see supporters getting behind the cause in the same way that they have in the opening games of the season as this is when we see the true value of their support, when we may be perceived as being up against it a bit.