"He was not so good. Now he's in good form. He has overcome the situation," Conte told reporters when asked about Cahill's mental state.
Mason is making good progress in his recovery after undergoing surgery.
"I understand how Gary is feeling - I'm pleased the guy (Mason) is well. I wish him and his family the best. I would hope to see him very soon on the pitch again," Conte said.
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Chelsea have reportedly had a bid for Celtic goalkeeper Craig Gordon rejected and Conte insisted his second-choice shot-stopper Asmir Begovic will be going nowhere if he cannot find a replacement during the January transfer window.
"Begovic will be allowed to leave if we can find a suitable replacement, but if not, he will stay at the club. For sure there is this Begovic situation," the manager added.
"Bournemouth asked about him but he's Chelsea's player. I'm happy with him."
Conte hinted he was likely to field a few fringe players when Chelsea host second-tier Brentford at Stamford Bridge in the fourth-round tie.
"We want to avoid a replay if possible, so we must try to win the game... Begovic will start tomorrow," he said.
"Nathan Ake can play as a central defender or wing-back. It's a good opportunity for him. Tomorrow's game is another chance for Michy Batshuayi to show his improvement."
(Reporting by Shravanth Vijayakumar in Bengaluru, editing by Ed Osmond)
