"And I was talking to a friend of mine, Zola Mazwi, a couple of months ago and he told me he knows of someone in the US, Tom Kindley, who is the (Free Jacks) high performance analyst.
"And within about two days we connected. They were interested in having me and I was interested in going over there. That's how it basically happened.
"My agent then got involved in the serious part of the conversations last month to get the deal over the line and within a short space of time I got a nice deal.
"It worked out perfectly because my Sharks contract was coming to an end at the end of this year. I obviously spoke to the Sharks, played open cards with them, and they were supportive of my decision."
The 29-year-old, who also captained his old school Dale College in 2008 and 2009, makes the American leap at a time when there's plenty uncertainty about southern hemisphere rugby since Covid-19's spread.
Shrinking professional contracts in South African rugby, unclear future plans around Sanzaar, have forced players and administrators alike to review their options. But Mtembu said the Free Jacks opportunity was one he couldn't let slip.
"I've been at the Sharks for 10 years and it's been great," he said.
"I just needed something different. It's just to close a chapter in my life. I've always wanted to play for one union in South Africa and I've been fortunate to be here for 10 years.
"But as a rugby player, your career is so short and I wanted to maximise it as much as I can. Going to America and playing in the MLR, an up and coming competition, is very exciting.
"I'm a big fan of the US, since I was fortunate to play in Vegas for the SA Sevens, so I got a taste of the country. I want to be part of that rugby growth in the US.
"I'll be joining the Free Jacks as a player and doing some coaching on the side. I'll be helping out at the academy as well. It's a massive opportunity and I couldn't let it slip. I cannot wait."
Mtembu joins South Africans such as New Orleans Gold and former Cheetahs flanker Vince Jobo and former Sharks team-mate Tendai "Beast" Mtawarira (Old Glory DC) in the US's MLR.