Gabby Agbonlahor is set to return from a calf injury for Saturday's match at Southampton, but Villa's team captain is struggling with a knee problem.
The team captain has barely trained over the past few days due to a knee problem and will face a late fitness test ahead of the Saints clash.
His potential absence could give Garde a major defensive headache with centre-back partner Ciaran Clark also suspended for the match, and the Frenchman admits that we could see the fit-again Jores Okore make his first senior appearance of the season alongside Joleon Lescott.
"He's struggling a little bit with a knee," Garde said of Richards. "I have to make changes. If a player is suspended the two central defenders will change. Clark has played the last three games with me, then it will have a change of course.
"I have more possibility in this part of the field. Jores Okore trained this week. He is fully fit."
Neither Liverpool loanee Tiago Ilori nor fellow defender Jose Angel Crespo will be options to feature on the weekend, however, although the former is close to shaking of the groin strain which has so far prevented him from making his Villa debut.
Gabby Agbonlahor, meanwhile, is in line to return from the calf injury which has kept him sidelined since last month’s 3-1 defeat at Tottenham Hotspur, but it remains to be seen how big a role he will be handed on the afternoon.
"Gabby has trained this week with the group," Garde added. "Tiago Ilori is still not fully fit to be selected. He is in a good way but he is not quite ready at the moment.
"Jose Crespo is not available for selection this weekend."
Another player who will definitely not be featuring at St Mary’s is Jack Grealish, with Garde confirming that the homegrown midfielder will continue to train with the Under-21s for the time being as punishment for his latest off-field incident.
The former Lyon manager stressed that the 20-year-old playmaker still has an important role to fill in his side amid their survival bid, but not until he has demonstrated that he is 100 per cent committed to the cause.
“He has trained this week with the Under-21s again because it was the plan with him – he knew that,” Garde said of Grealish. “I know when he will return to the team – he knows as well – and when he will, I will tell you.
“Like every player, Jack made a mistake. He has to pay the consequences for that. If another player does something wrong, he will have the same treatment.
“But Jack is young and he will be back in the team. When he is fully committed to his job, he will be a good player.
“When we are playing games, we can think we are kids, but we are not – we are in a big competition. To achieve what we should achieve, we need to be 100 per cent focused on our job and prepare the way we need to win games.”