Emmanual Onariase will start a second loan spell with Cheltenham Town in January.
The Rotherham United defender will link-up with the Robins from Boxing Day, but he will not be able to play until the match at Colchester United on January 6.
Onariase was at Barnet on Saturday to watch the Robins pick up a 2-0 win thanks to first half goals from Kevin Dawson and Carl Winchester.
He will return to the Robins, having spent the second half of last term on loan from Championship club Brentford.
"He hasn’t come here if he isn’t going to join us and he certainly isn’t joining Barnet!" Gary Johnson said after the final whistle at The Hive.
"It’s 99.999% certain that he’ll be joining us, from Boxing Day.
"We have him in for 10 days before he can be selected on January 6.
"He is looking forward to it and it's nice that players want to see what they are going to be coming into.
"He improved over the course of last season, which got him his move to Rotherham, so it's only fair now that we get the best of him in the next half of the season.
"He’s a lovely lad and will come into the group comfortably."
