The Gunners have long struggled at the heart of defence, with David Luiz failing to convince since his summer move from Chelsea, Laurent Koscielny departing and Shkodran Mustafi widely distrusted by the coaching staff and fans alike.
Saint-Etienne youngster William Saliba will arrive at the club in the summer of 2020 but Keown was impressed by the Colombian pairing, who both played in the Belgian side's loss to Liverpool on Wednesday.
"(Cuesta) looks some player by the way, both Colombian central defenders look pretty decent," he told BT Sport.
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"If I was an Arsenal scout - and never have been, never been asked to comment ever as a former player on prospective purchases - these two are not bad, I can tell you."
Arsenal were also widely linked with a move for Red Bull Leipzig's Dayot Upamecano in the summer and are rumoured to have retained their interest in the Frenchman.
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