Sinisa Mihajlovic was disappointed he had to turn to his bench after AC Milan defeated Crotone in extra time.
Milan were pushed by Crotone but advanced to the Coppa Italia last 16 after overcoming the Serie B high-flyers 3-1 at the end of extra time on Tuesday.
Luiz Adriano and Ante Budimir exchanged goals as Milan struggled to breakdown Crotone before Giacomo Bonaventura and M'Baye Niang came off the bench to win the match in the additional period.
Speaking to reporters afterwards, Mihajlovic said: "There are no easy victories as every match is played on the field.
"I didn't expect to play extra time as I was convinced we would win. I wanted to keep the likes of [Carlos] Bacca and Niang on the bench but in the end I needed them.
"When Bonaventura, Niang and [Riccardo] Montolivo came on we improved in terms of quality. Some the players that started did well while others didn't, but that was to be expected as they rarely play.
"Along with that, Crotone showed they are a difficult team to play against and they had the backing of the many fans that came to San Siro."