Southampton boss Tonda Eckert has said that defender Welington will be out for a "couple more weeks" with a muscle injury.
The 25-year-old was forced off in the final moments of Southampton's dramatic win over Leicester at the King Power 10 days ago, and will now face a spell on the sidelines.
While giving an update on fitness in the squad, Eckert also confirmed that captain Jack Stephens had been given the all-clear regarding his fitness after undergoing a scan.
"Welly is going to still take a couple more weeks with a muscle injury, not the best [news] but hopefully it won't take too long," Eckert told BBC Radio Solent.
"Jack's scan came back fine, so he will be available for tomorrow. The only other one was Jay [Robinson] who struggled a little bit with his quad, so he will be out for tomorrow, and we need to manage this over the next week and then get him back quickly."
Welington has made 15 appearances for Saints so far this season and has impressed since being handed more minutes after the turn of the year.
Southampton have climbed up the table in recent weeks with four wins in their last five matches, sitting ninth in the Championship table.
"It's all set up and now it depends on us," Eckert added.
"We have made some progress over the last weeks but still at the same time we are far away from where we want to be in the end, now is the moment to keep pushing and stay on the gas.
"The whole club has come together over the last few weeks, the group has come further together and we are increasing our intensity by each game.
"In general things are going in a good direction but we need to prove that every single time we step on the pitch."
Saints welcome back former head coach Nathan Jones on Saturday who brings his Charlton side to St Mary's.