The right-back played well against Sunday's opponents, Newcastle United, in our 2-0 Carabao Cup final victory at Wembley in February.
Aaron was introduced for Diogo Dalot - our starter on Tyneside - at half-time of that game and helped shut down Eddie Howe's side and secure a first trophy for United under Erik ten Hag.
The Reds will have to make do without our no.29 in the north-east though, as we seek to extend our three-point lead over the Magpies, who currently sit fifth in the table.
“Yesterday, in the night he didn’t feel very good,” the manager told MUTV’s Stewart Gardner.