Fiorentina and Napoli will be top seeds in the Europa League draw, but Juventus and Lazio go into the second pot.
The Round of 32 will be formed on Monday and include the teams dropping down from the Champions League.
Sides from the same country cannot face each other, nor can they take on an opponent already played in the group phase.
Fiorentina are seeded, as they won their Europa League group, while Napoli are also in Pot 1 after accumulating 12 Champions League points.
Rafa Benitez’s men became only the second side in the tournament’s history to go out despite notching up 12 points, after Paris Saint-Germain in 1997-98.
Fiorentina, Napoli, Valencia, Ludogorets, Salzburg, Rubin Kazan, Eintracht Frankfurt, Genk, Sevilla, Lyon, Trabzonspor, Tottenham, AZ Alkmaar, Benfica, Basel, Shakhtar Donetsk
Juventus, Lazio, Ajax, Porto, Viktoria Plzen, Swansea, Chornomorets, Esbjerg, Maribor, Dnipro, Maccabi Tel-Aviv, Dinamo Kiev, Slovan Liberec, Betis, Anzhi, PAOK