Davies was a try scorer in that fine showing at the Stade Jean Dauger but Scotland international Southwell hasn't featured at all this term as he struggles with a troublesome hamstring injury that shows no sign of letting up any time soon.
"He's not progressing at all. It's getting to the stage where we're starting to fear the worst," Young told the Bucks Free Press in relation to Southwell's situation.
"We're still pushing ahead with it, but it's not moving anywhere near as quick as Hugo would like or we'd like."
Wasps' form is definitely moving in the right direction, though, with the 2003 Amlin Challenge Cup winners and double Heineken Cup kings having won six of their last seven games in all competitions.
They produced another fine showing to leave France with a hugely important win last week and Davies is looking for more of the same on Sunday when they face a Viadana side whom they scored 14 tries against in Italy back in October.
"We've got some real momentum at the moment, everyone is excited to pull on the jersey and we all want to play a good brand of rugby," Davies, who has just signed a new contract, told the Wasps website. "We have to treat Viadana with respect but we know that if we turn up with the right attitude there are five points on offer.
"We have played Bayonne the past three seasons and that is the first time that we have been able to go down there and win away. It is a great achievement for the boys - it is always difficult to win away, especially in France. It was a great team effort.
"We have spoken at the start of this week about how this game is a bit of a mental test and it is about us, we can decide how this game is going to go. We took them apart at their place but this weekend we have to approach the game in the right mind set. We are all excited to play this weekend, which is a great thing."