A bad result for Spurs, extremely disappointing, though in truth it could have been worse. Ajax totally bossed the first half, Donny van de Beek sending Hugo Lloris off for the paper and slotting home, and could easily have gone in with a bigger lead.
Tottenham make four changes to the side that lost to West Ham on Saturday.
Son Heung-min is suspended, while Eric Dier, Juan Foyth and Ben Davies drop to the bench. Taking their spots: Fernando Llorente, Victor Wanyama, Jan Vertonghen and Kieran Trippier. Moussa Sissoko is back, but his groin problem limits the midfielder to a place on the bench.
Ajax are at full strength, making just one change to the team that swatted aside Juventus recently. David Neres comes in for Kasper Dolberg.
Tottenham will be looking to turn the deficit when they go to Amsterdam next week Wednesday for the second leg.