Arsenal will miss the services of Hector Bellerin after the full-back received his fight yellow card of the season during the defeat to Burnley on Sunday.
Nicolas Pepe will be available for selection after completing a three-match Premier League suspension.
Here is the report from Arsenal;
David Luiz: sustained a deep laceration to the head during Wolves (h) on November 29. Due to the significant impact David has continued to be closely monitored for a concussion and has followed all protocols. David is now back in full training and his fitness will continue to be assessed ahead of Wednesday’s match.
The best wishes of David and everyone at the Club continue to be with Raul Jimenez and his family.
Gabriel Martinelli: Left knee. Sustained injury during training on June 21.
Gabi is now back in full training.
Thomas Partey: Left thigh. Sustained a strain to the left thigh during Tottenham Hotspur (a) on December 6. This is in the same area of the thigh as the initial strain which Thomas sustained against Aston Villa (h) on November 8.
Thomas will be unavailable for forthcoming matches and is working hard with our medical team in order to return to training as soon as possible.
Nicolas Pepe: Available for selection after completing three-match Premier League suspension.
Granit Xhaka: Suspension. Serving the first of a three-match suspension. Will be unavailable for Southampton (h), Everton (a) and Manchester City (h - Carabao Cup QF).
Follow Arsenal vs Southampton live on Futaa.