Villarreal beat United in the ECL final and Atalanta beat us at Anfield during the group stage. I get United has gotten Varane and Sancho since, but the ace in Villarreal and Atalanta's hand is Ole.
Atalanta did win at Anfield, but keep in mind that Klopp fielded a weak lineup as the group was near enough won at that stage.
Ahead of the game with Atalanta the table looked like below, and we still had a home game against Ajax to come, and what became a dead-rubber against Midtylland.
Neco Matip Rhys Tsimikas
Salah Origi Mane
We only registered 4 shots and 0 on target so the performance and result reflected the patchwork selection. I highly doubt Atalanta would have stood a chance with Trent, Robertson, Van Dijk, Fabinho, Henderson, and Firmino/Jota on the pitch (in fact they lost 5-0 when we had a stronger team).