Now he cannot wait for an opportunity to run at twin brother Peter in Wellington on Saturday night.
He might have to get through Julian Savea as well, but that is just fine by him.
The Highlanders second five has had a dreadful run of injuries during the past three years.
The powerfully built 24-year-old made his debut for the franchise in 2018 and showed some promising signs.
But his development got derailed and he is very keen to get back on track.
Umaga-Jensen made an impact off the bench in the 26-16 loss to the Chiefs in round one, and formed a physical combination with Fetuli Paea in the spirited loss to the Crusaders last week.
He is odds on to start against the Hurricanes and that will potentially put him on a collision course with Savea and perhaps even his twin.
Savea started at second five for the Hurricanes in the dramatic 33-32 last-minute win over the Blues on Saturday.
The former All Black came to life in the final quarter and busted a few tackles to help set up the final try, while Peter Umaga-Jensen made an impact off the bench.
"Just to be able to play against him is quite cool, and especially against my brother," Thomas said.
"I haven’t actually run at [Peter] or he’s tackled me and I’ve tackled him [at Super Rugby level], so hopefully there is an opportunity for that in the weekend."
Plenty of that happened in the backyard, of course.
The fraternal twins share more than just a Wainuiomata address growing up and a talent for rugby. They have the same tattoo on their left forearm — a 21st birthday present.
It is a nod to their Samoan heritage but also has Maori and Cook Island elements.
The game against the Crusaders on Friday was Umaga-Jensen’s first 80-minute game in Super Rugby since 2019.
"The body was really sore. It wasn’t just the shoulders, but the legs and the lungs and everything else.
"But in terms of looking forward ... hopefully with more games I’m just hopeful it will get better and better and the aches and pains won’t be as bad."
He has to get the recovery right, but that certainly beats the past two or three years which have mainly been about rehabilitation.
"Yeah, it was annoying and tedious as well. I kind of just got stuck in a routine where I was just coming to the gym and doing what I had to do in terms of rehab and watching the boys.
"I’m not going to lie, it was really tough over those two or three years."
Players alongside him were going through the same
process which had helped him to remain motivated.
Nothing like a bit of sibling rivalry to keep you focused too.
"I knew I wanted to be in this business. I want to play rugby. And also I have some competition with my family.
"My brother ... is also one of my biggest supporters, so he was kind of in my ear helping through those times."
Peter played one game for the All Blacks in 2020.
Highlanders coach Tony Brown has been vocal about Thomas’ own prospects of playing international rugby.
"My real goal was just to get back in to rugby and kind of just be able to play. And just being able to play now, it’s just great," he said.
Playing for the All Blacks remains a dream but the more immediate focus is helping the Highlanders post a first win this season.
His combination with Paea is an area the Highlanders believe they have an edge.
The challenge for the Highlanders is to capitalise out wide. There will be another change in the back three this week.
Outside back Josh Timu picked up a knee complaint in the 34-19 loss to the Crusaders. The injury was being assessed yesterday and the Highlanders are hopeful he will not be sidelined for too long.
Prop Ethan de Groot (rib) and James Lentjes (neck) both sustained injuries during the Crusaders’ game but are back training, which is good news for the franchise.
