Cowdenbeath find themselves bottom of the table after a third successive home defeat.
They are two points adrift but these points cover five teams, and Blue Brazil boss Liam Fox is set to strengthen his squad this week in a bid to get some consistency.
This was a dull game with neither side creating many chances. It looked odds on a goalless draw when slackness by Cowden allowed Berwick’s Steve Thomson to head home the winner six minutes from time following a corner.
Cowdenbeath were without suspended midfielder Fraser Mullen and it seemed to affect their control of the game. Too often they opted for the long ball, which was easy meat for the tall Berwick defenders.
Only a couple of Kris Renton shots which were blocked threatened Rangers.
“After the really good all-round show at Stirling that was not good enough at all,” Fox said. “I praised the players for their show at Stirling but they have to take responsibility for a disappointing overall performance against Berwick.
“They are having to learn fast that using the large areas of space on the big Forthbank pitch to move the ball about well is not something that is available at Central Park and you have to battle hard for possession in home games.”
He added: “I am hopeful of bringing at least two players in, and that will help us get some consistency.
“There are areas of the team that need strengthening and I have a few targets in mind, and while it might take time to get them all aboard I would hope we can get two in the side for this week’s home game with Edinburgh City.”
Berwick were bottom before the game, and their boss John Coughlin was delighted with the attitude shown by his team.
“It really was dour stuff but we defended much more solidly than in recent games and I felt that we just edged it over the 90 minutes,” he said.
