- The two sides meet in the Europa League on Thursday.
- Smalling has recently recovered from a knee injury.
"It was important to get Chris at least 45 minutes of playing time, he had more than that, and I think it was positive. Now he has the chance to play against Manchester United.
"Unfortunately, we were unable to give some playing time to all those who were coming back from injury, but Chris and [midfielder] Leonardo Spinazzola were the most important ones to get minutes in their legs."
Smalling has recently made his return from a serious knee injury that kept him on the sideline since early March. Earlier this season, the defender struggles with a muscle problem as well.
The former Man United centre-back has made just 18 appearances across all competitions for the Serie A side this season with injuries limiting his potential playing time.