Boruc had recovered from the knee operation which opened the door for the former Dundee United player the chance to impress during the previous eight games where he had arguably been Celtic's most consistent player.
"They took the news in a very professional way," Mowbray said.
"You make decisions every week, Zheng Zhi or Barry Robson, Fortune or Samaras, Lukasz or Artur.
"Those are the decisions you make every single week in every position so it was no harder than any other conversation you have with a footballer.
"I think they have great respect for each other, they are the same nationality and work very closely in training.
"Lukasz was very supportive of Artur and focused on making sure he was ready for the game."