Austin is set for an unspecified spell on the sidelines after being substituted in the first half of Thursday night's 1-1 draw with Hapoel Be'er Sheva at St Mary's Stadium, which ended the Saints' hopes of progress through to the knockout stage
Puel confirmed the extent of Austin's injury, to the same shoulder he has twice had surgery on, had not yet been fully assessed when he faced the media on Friday morning as his squad regrouped for Sunday's visit of Middlesbrough
"For the moment, I don't have all the news
He's not available for Sunday and we will see later what the full answer is and how long he will be out for," Puel said at a press conference
"It is a disappointment for him because he has had a good first part of the season, but it's important for the team to have a good answer with a different offensive player
"We will see the quality of other players
We are a group, a collective, and it is important to consider all of this, not individual things."
Serbian midfielder Dusan Tadic could feature against Boro having come off the bench on Thursday night following his return from a broken nose, while Puel could also bring back captain Jose Fonte along with Jay Rodriguez and Sofiane Boufal
Whatever side he sends out on Sunday, Puel is expecting a response as the Saints look towards climbing back into the top half of the Premier League table
"It is important to stay now with good concentration on the last games of the year," he said
"It is a very important game now to come back with authority and with conviction, to get moving again in the Premier League with a good spirit
"I am sure we have to have the good reaction because I have competitive players and on Sunday we will see this."
Puel defended his side's approach to a match where Southampton needed only a goalless draw to progress and bring an end to a European campaign which had looked so positive following victory over Inter Milan last month
"I understand all people have a strong disappointment, the fans and all of the people in Southampton," said the Frenchman, who was appointed in the summer following the departure of Ronald Koeman
"We touched the qualification (for the knockout stages), it was just down to details, but we gave all of our possibilities with spirit
"We like this competition (Europa League), we gave our all for this and were unlucky, like when the opponent had just one shot and scored a goal
"But now if we like this competition, then it is important to come back, to look forwards and with a positive attitude to win our next game in the Premier League
"This is a good road for us."
Source : PA
Source: PA