Ajax will be without Tagliafico on the left wing for the return leg. He got a yellow card and is suspended for the 2nd match. Lasse Schone limped off because of an injury, I don't know how serious that is. Ajax is also still fighting with PSV for the league title so they can't afford to play badly in the league meaning they have to filed a strong lineup during the weekend. Juventus on the other hand has an 18 points advantage in the league and will be playing SPAL. At least 7 starters will be rested during that match and that could end up being the advantage the Juve needs to qualify for the next round.
I think it would be very unwise of Juve to sit back and think they've got this in the bag. Ajax could be the dark horse of the tournament. They turned over Real Madrid away and I think RM seriously underestimated them having a 2-1 advantage from the first leg and two away goals and it cost them in the end. Real Madrid might not be the team they were the last few tournaments but all they were really missing was Ronaldo and Zidane. I think Real probably will win at home but they certainly should'nt take their foot off the gas and assume this will be a walk-over.
My initial prediction was correct. Juventus will be resting many first team starters for tomorrows league match so they can be 100% fit for the return leg VS Ajax.
Take a look at the called up players VS SPAL that features some U21 players as well:
1. Szczesny 2. De Sciglio 6. Khedira 10. Dybala 12. Alex Sandro 15. Barzagli 16. Cuadrado 18. Kean 19. Bonucci 20. Cancelo 21. Pinsoglio 22. Perin 30. Bentancur 33. Bernardeschi 37. Spinazzola 38. Coccolo 39. Kastanos 40. Mavididi 41. Nicolussi Caviglia 43. Gozzi
Source:
https://www.juventus.com/en/news/news/2019/squad-list-for-ferrara.php