That is the view of former footballer Tony Cascarino, who spoke about the future of William Saliba and several other stars.
Saliba is being linked with a move to Real Madrid, while fellow central defender Gabriel Magalhaes is also a target for other top clubs.
On talkSPORT, Cascarino said: "There are vultures in football hanging over football clubs all the time and trying to take their best players.
“There’s no bigger vulture than Real Madrid – if they’re after you then there’s a good chance of it happening.
“It’s not only convincing the player, but the agents get involved and the lure of Real Madrid.
“Look, winning and being successful is a great way of keeping players, it really is.
“Arsenal have to achieve that because Saliba is playing to the level of being a Real Madrid player but he’s got to be convinced that Arsenal are going to be a successful and winning team.
“They need to be challenging to win the Champions League because that’s what Real Madrid do so often.”