Boyes is currently at League One side Wycombe Wanderers on a season-long loan from the Blades.
The defender played in League One last season with Forest Green Rovers, who were relegated, and Lincoln City, and faced Rak-Sakyi, who was on loan at Charlton Athletic.
This season however, the Eagles have not allowed Rak-Sakyi to leave the club on a loan despite a host of Championship and League One sides trying their best to sign the winger.
Boyes revealed that Rak-Sakyi is the hardest opponent he has faced so far and stressed that the 20-year-old has a bright future ahead of him.
“Rak-Sakyi”, Boyes told Wycombe’s in-house media when he was asked who is the toughest opponent he has faced.
“It’s just, he is an inverted winger.
“You can tell that he is going to have a top career.
“He’s real good.”
Rak-Sakyi has only managed eight minutes of Premier League football and he will be looking to get some first-team minutes in Roy Hodgson’s team.