Arsenal manager Arsene Wenger denied introducing Alexis Sanchez off the bench against Sutton United was a risk.
Wenger's side closed out their two-goal victory on Monday to set up a quarter-final clash with Lincoln City.
The 67-year-old later said he was always confident Sanchez could deal with game time off the bench.
"He is a guy who has a strong body," he said.
"I think on this pitch it is the guy who does not have good co-ordination, who is heavy on his feet, who is in trouble.
"Alexis is more a guy who has very good co-ordination, he is light on his feet. I don't think it was a risk."