The Liberty Stadium outfit, who have won their last two RaboDirect PRO12 fixtures, sit five points behind fourth-placed Glasgow Warriors, who have played a game more, and Humphreys wants to close that gap with victory at Rodney Parade.
"This period of three games in nine days is crucial for us and having won the first game, against the Scarlets, it really is vital that we keep on working hard as a group, looking to improve and to find the performance level that will get us into the play-off spots before the PRO12 goes into a break for Europe and the LV," he said.
"As a coaching group, yes we've got to be pleased with the win against the Scarlets, but there's still room for improvement.
"We showed great effort and commitment, good discipline and we played the game plan well but there were areas of the performance where we could have done better.
"With the quick turnaround and the nature of Christmas rugby there's not much time to prepare for this game but what time we have got will be used to ensure the boys are focused and know what is needed to raise the performance another level again.
"It's another tough week, with a difficult game in Newport followed by another tricky one at the Liberty against Zebre on Friday night.
"We have to make sure that everyone understands how important these games are to our PRO12 hopes, that we need to put top-level performances in, and if we do that, then we have a chance of getting the results we need."
Ospreys' only defeat in their last eight RaboDirect PRO12 encounters was 13-23 to Edinburgh at Murrayfield on 23 November - but they have not won away from home in any competition since a trip to Zebre in the RaboDirect PRO12 on October 5.
Newport have been handed a boost in their bid to topple their Welsh rivals with the return of Tom Prydie after a knee injury.
Other changes to the side include the half-back paring of Lewis Robling and Jonathan Evans.
There are no changes in the forwards pack after the narrow Boxing Day defeat against Cardiff Blues - and outside-half Dan Evans has not recovered from his ankle sprain in time to be considered for selection.
The Dragons have won just one of their last six RaboDirect PRO12 contests - 14-3 at home to Connacht on November 23 - but director of rugby Robert Beale wants to repay the faith of the fans.
He said: "Everyone at the Dragons would like to thank all the fans who travelled to the Arms Park on Wednesday, the vocal support we received from the fans was fantastic."