The six-foot-seven-inch forward impressed against Liverpool with his strength and agility as he slowly makes his way into the first team after a long period on the sidelines.
Onuachu is a target for Club Brugge this January in a move that Martin does not want to happen if possible. Martin spoke on the deal and how he believes many clubs will be after him as soon as the transfer window opens.
"Yeah, I think so. I think if he was going to go it would have been in the summer for the club to reinvest some money.
"At the time, it was a few clubs interested but none of them were anywhere near serious enough for us to consider and I think Paul was just caught in limbo a bit.
"I think he thought he was going to leave and it hadn't quite worked out, last summer he was here for probably five or six weeks before he was going.
"The whole time it was planned he was going to go because he cost a lot of money and he wanted a challenge at the top level if he could but he was brilliant.”
The Saints boss reiterated that he wants to keep the towering striker if possible, but cannot help if he is unhappy and wants a move elsewhere to find more minutes on the pitch.
"He was respectful and then so in January I'm sure there will be a few people that are interested in him again," continued Martin.
"I'm sure there will also be a few people kicking themselves that they clearly didn't quite want him enough in the summer.
"For me, if Paul is happy, we're really happy and we want him here as he can help us achieve what we want to achieve this season."
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