The 40-year-old has been ruled out of the rest of the LV= Insurance County Championship clash in Cardiff, with Ripley admitting the injury could be serious enough to keep him out of the Steelbacks' Royal London One Day Cup campaign as well.
Berg suffered the injury in the warm-up, with Ripley saying there was 'no-one near him'.
The former Hamspshire man underwent a scan, and although he is still awaiting the results, Ripley is fearing the worst.
“It’s not good news on Gareth Berg " said the head coach.
"He’s had a scan and we are still waiting for the results of that, but he’s on crutches and it’s not looking good at this stage.
"He won’t play in the rest of this game and I’d be surprised if we saw him in the 50-over competition now.
"He fell over on his ankle in the warm-up with no-one near him."
Berg's absence has left Northants short in the clash against Glamorgan, as he was unable to bat in the first innings which saw the County close on a below par 215 for nine having won the toss and batted.
The County are also a bowler down, and Luke Procter is going to have to step up to fill the void.
On another rain-hit day, Glamorgan had reached 52 for two at the close, with Ben Sanderson and Procter claiming a wicket apiece.
Former Lancashire man Procter is a recognised all-rounder, but has barely turned his arm over so far this season, and that will change in Cardiff.
"Luke Procter is on the team sheet to bowl and it was good to put him out there," said Ripley.
"He’s a good bowler. He was one of four seamers, but now he’s one of three.
"Hopefully Simon Kerrigan might come into the game and lessen the loss of Gareth, but it still looks a good wicket."
Looking back on the first two rain-affected days, Ripley said: "We’ve started both days well but the disappointing thing is we’ve worked hard and then lobbed a few wickets away.
"There were too many caught in the ring which is never a good sign.”