Southampton manager Ronald Koeman has confirmed that Shane Long suffered a rib fracture during their 3-2 FA Cup loss against Crystal Palace on Saturday.
The striker came on as a second-half substitute, but only lasted 20 minutes and had to come off following a collision with Palace's Joel Ward.
After the game, Koeman told reporters: "It's a pity, because he [Long] is doing well."
Palace twice came from behind during the game and eventually sealed victory thanks to a strike from Marouane Chamakh.
Southampton will be looking to make amends for the loss when they take on Swansea City in the Premier League next week.