United are considering a change at left-back - as Luke Shaw is out of contract next summer and could possibly move on from Old Trafford - with Newcastle United defender Lewis Hall still on their radar.
Liverpool boss Andoni Iraola is in a similar position over Milos Kerkez at Anfield and that could trigger a move into the January market and again ahead of the 2027/28 campaign.
Palace defender Tyrick Mitchell has emerged as an option due to his consistency for the Eagles since 2020 with 250 Premier League appearances racked up.
The latest from Caught Offside claims Chelsea are now in the running for Mitchell, despite signing Pep Chavarria as a summer replacement for Marc Cucurella, with Alonso unconvinced by his fellow Spaniard.
Palace could make one final contract extension pitch to Mitchell before the end of 2026, but they will push to sell in January if he's unconvinced, as they did with Marc Guehi to Manchester City earlier this year.