Glenn McCrory told Sky Sports that Brian Rose battled through nerves to knock off former world champion Joachim Alcine in Blackpool on Saturday night.
Rose - who snared the Lonsdale belt outright in October - secured a 12th-round stoppage of one-time WBA light-middleweight titlist Alcine, 37, in his maiden foray up to world level.
McCrory says there were signs that The Lion was "afraid" during his bout with the wily Canadian, who was floored by Brit Matthew Macklin in one round at middleweight last September.
But he reckons 28-year-old Rose showed real grit to come through the clash and feels that he can continue his ascent if he loosens up and gets a few more morale-boosting wins under his belt.
"Rose looked and boxed like he was showing too much respect to Alcine and could have controlled the fight much earlier than he did," said McCrory, a former world cruiserweight champion.
"He could have really hurt Alcine, but I think he was afraid to do that because it was his first step up to world level and he was in the unknown.
"But he showed character towards the end, and when it looked like the scores were becoming level he managed to pull the win out of the bag.
"He rose to the challenge and that's the mark of a champion. He is a better fighter than we saw tonight [Saturday] but having got the stoppage he will now be confident.
"He needs a couple more 10-rounders as I'm not sure he is ready for a European championship shot just yet, as you saw in this fight that the top half of his body was very static and he was easy to hit.
"But I think a lot of that was down to nerves and toward the end of the fight he was making Alcine wobbly and connecting with punches to the head, so he is learning and improving all the time."
Ex-Commonwealth light-heavyweight champion Nicky Piper, who joined McCrory on the Sky Sports punditry team, added: "It was a young fighter in with an old master - and the old master, Alcine, was the better boxer, but he couldn't sustain attacks for longer than 10 or 20 seconds.
"Alcine had the better of Rose at times when he let the punches go, but eventually tired and lost his energy and that let Brian hit him with some accurate punches - but it was still a good win for the Brit."