Cathcart came through the United system and played with the Shanghai Shenhua-owned striker at Vicarage Road.
"I'm delighted for him, to be honest," Cathcart to manutd.com.
“I know it's something that he'll be really enthusiastic about, because he was an ambitious player.
“It's an amazing opportunity for him and I'm sure he'll do everything in his power to make the most of it."
“He can adapt. He's got good link-up play if you do play with two strikers, and he can also hold the ball up if you want to go with the one striker," he assesses.
“He can run the channels as well, because he's got good pace and good strength and he's always a threat in the box."