Moussa Djenepo has become Southampton's first signing under manager Ralph Hasenhuttl.
The winger joins from Belgian club Standard Liege, where he scored eight league goals last term, for a reported £14 million ($17.8m) fee.
Djenepo, 20, is a Mali international and part of their squad for the upcoming Africa Cup of Nations.
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"It is something I am very proud of," he told Southampton's website. "It's a dream come true. Southampton is a great club and I am very happy.
"It's a good club that is progressing, it has great facilities, and it's a place that can help me to really kick on and progress.