Gower was injured in the first State of Origin match last month and was expected to be out for at least four weeks.
Media reports today suggested he may make an early comeback, especially given Penrith�s halves crisis, but Lang says that won�t be happening.
�We'll take it one week at a time but we are not going to risk playing him too early,� Lang told the post-match media conference. �He won't be back on Friday.�
Gower himself told Fox Sports that he will be back in training tomorrow and is hopeful of returning against the Dragons.
Gower�s injury along with injuries to Preston Campbell and Ryan Girdler forced the Panthers to use winger Amos Roberts at halfback today against Manly, cutting out the enterprising play the side are renowned for.
"It was a tough ask of Amos at halfback and the amount of work he had to do took away from his running game,� Lang said.
Penrith were among six favourites to be beaten in matches this weekend, following in the footsteps of the Sydney Roosters, Newcastle, St George-Illawarra, Canberra and the Sharks.
Lang said that he was disappointed in the performance, given the side�s tremendous effort against competition heavyweights the Bulldogs last Sunday.
�It's a bit disappointing. I thought we took a step backwards today,� he said.
Penrith will not only be without their injured stars next weekend, but are also expected to be without Rhys Wesser, Ben Ross, Trent Waterhouse, Luke Lewis and Luke Rooney, all of whom are expected to be selected for the second State of Origin match in Brisbane.