The 22-year-old made two costly errors and was taken off after 17 minutes by Igor Tudor with Tottenham 3-0 down in the first half against Atletico Madrid the Champions League on Tuesday.
Tottenham went on to lose 5-2 at the Wanda Metropolitano but the biggest story was Kinsky who looked distraught as he walked down the tunnel.
The goalkeeper has been shown a lot of support from fellow goalkeepers including David de Gea and now Courtois who reveals he contacted the Spurs star.
"I sent that guy a private message," he told Ziggo Sport. "I know it's sh*t for him, but he's well surrounded by his club, so this will work out.
"I also made mistakes at Atletico and Chelsea. And when Messi once kicked two balls through my legs, I got a lot of flak too.
"It wasn't as bad as it was for him, but I know this is very difficult. I told him to see it as a learning experience. He has talent and needs to keep working hard. The fact that he was in goal also means the coach had a lot of confidence in him."
Kinsky did not speak after the game but has now made a post on Instagram of him re-watching the match on television.
“Thanks for messages. From dream to nightmare to dream again.”
Spurs now travel to Premier League champions Liverpool on Sunday afternoon where Guglielmo Vicario is set to start between the sticks for the North London side.