Both players had to come off during their 3-0 loss to Arsenal at the Emirates Stadium.
The forward duo are key goal threats for the Saints this term, and manager Ralph Hasenhuttl knows he may have to dip into the transfer market if their injuries are long term.
Asked about the situation, per theDaily Echo, Hasenhuttl said: "We don't know yet. Hopefully not too serious.
"But it was not possible for them to continue.
"The signs before the game haven't been the best today, and hopefully we have not more injuries now because a tough time of the season is coming."
When asked if the injuries could change his transfer plans, Hasenhuttl added: "We will look how serious it is, how long they are out and then we will look."
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