Cheltenham look set to be without defender Michael Hector for the crunch tie.
The 20-year-old sustained a rib injury early in the second half of the Robins' 1-0 first-leg defeat on Thursday night and was taken to hospital.
"Michael Hector has gone to hospital for an X-ray and hopefully it's only precautionary, but whatever happens we'll deal with it," said Robins manager Mark Yates, who has no other new selection problems.
Billy Jones replaced Hector at Sixfields, with Keith Lowe switching to centre-half, leaving Yates with a possible selection dilemma for the return leg.
Striker Paul Benson returned to the starting line-up at Northampton following an ankle injury and lasted the full 90 minutes, so is expected to resume alongside Byron Harrison.
Northampton skipper Kelvin Langmead and Clive Platt could return to play some part in Sunday's encounter.
Defender Langmead returned to the bench for the 1-0 first-leg win after being sidelined since the end of March with a knee injury.
Striker Platt (calf) had missed the previous three games before also being named among the substitutes on Thursday night and both players will be hoping to feature.
Winger Ishmel Demontagnac lasted 76 minutes in the first leg after returning from a hamstring injury and will be monitored, while leading goalscorer Adebayo Akinfenwa and winger Chris Hackett played key roles for the Cobblers having been rested in recent matches.
Manager Aidy Boothroyd has no major new problems as his side look to defend a slender one-goal advantage.