The pair have been reunited after working together when Rosenior was a senior player at the Amex from 2015 to 2018 and Sanchez was a young goalkeeper from the club’s academy.
They appeared only once in the same starting XI for a competitive fixture, a 3-0 defeat away against Coventry in the EFL Trophy for the under-23 team, with Rosenior withdrawn at half-time for the now-Arsenal defender Ben White.
He refused to confirm Sanchez as his first-choice keeper following the Carabao Cup defeat to Arsenal, during which the Spaniard made two errors leading to goals, but nevertheless praised the 28-year-old for making a number of other important saves.
“I trained with Rob, I coached him with Brighton’s under-23s,” said Chelsea boss Rosenior.
“At that point we knew what his potential was.
“I said when I came in, I’m so proud of him. To be at this club, to see how his career’s progressed, and off the pitch as well. He’s got two children. I saw Rob when he was 17 years old, when he was a kid, talking about when he passed his driving test.
Chelsea's Moises Caicedo, Marc Cucurella and goalkeeper Robert Sanchez (Image: Martin Rickett/PA Wire)
“I’ve got a great connection with him. The scary thing with Rob is I can see how much he can improve as well.”
Rosenior said after the loss to Arsenal that any mistakes Sanchez might make are “on me,” a reference to the way in which he asks his goalkeeper to take part in the play.
A particular strength the Spaniard has demonstrated this season has been his distribution with his feet. During the 2-0 win over Brentford on Saturday he executed a number of highly impressive long balls that set Chelsea attacks into motion.
“Always play to a player’s strengths, whether it’s your goalkeeper or your number nine,” said Rosenior. “You want them to be comfortable and to play the way that they’re comfortable.
“Rob has already shown his fantastic distribution against Brentford. A couple of long passes to Pedro Neto that we nearly scored from.
“You always want to improve every player. That’s not even speaking about weakness. It can be making their strengths even better.”