Arsene Wenger has moved quickly to wrap up a deal for the France Under-21 striker.
The 20-year-old is out of contract in the summer but Arsenal will still need to pay compensation under the Bosman ruling. And the Gunners boss said: "I'm very confident.
"We are advanced with him but it is not done. He is a young striker who is promising. He has a big talent."
Wenger will consider loaning him out but the youngster could be part of the Arsenal first-team squad next season.