The 27-year-old prop made his debut when Rhinos slumped to a 28-16 defeat at Salford Red Devils in Super League round 14.
It was difficult circumstances for the Sydney-born New Zealander, who had been in the country only two days and trained once with his new team-mates.
Seumanufagai, who had never previously visited this country, admitted he is still getting over the effects of jet-lag and barely slept before the game.
He said “I didn’t realise it would take that much out of me, the flight.
“My body clock is a bit out at the moment. That game should help and, hopefully, I’ll sleep better now.
“I was awake at 3am on Friday – wide awake – and I stayed awake after that.”
Of his first taste of Super League, he added: “It was okay just to get the cobwebs out. There’s a few things to work on for myself, but that will come in the next few weeks with some game fitness. The game was very fast, really quick play-the-balls. The speed on attack is something I have got to work on.
“I didn’t know what to expect so it was good to get a first taste. I know a lot of the boys come over here from the NRL so I couldn’t imagine it would be any different – and it was a lot faster at times as well.”
Rhinos’ performance followed a familiar pattern.
They trailed 12-0, halved the deficit on the stroke of half-time and then conceded 16 unanswered points before finally getting their game together in the closing stages when they ran in two consolation tries.
Leeds remain firmly in the relegation battle, but the former Wests Tigers and Cronulla Sharks forward insisted he saw encouraging signs.
“The communication between players was good, everyone is staying positive,” he noted. “They have had a lot of games in the past few weeks so this week we are back to the drawing board and working on what we need to work on.
“Absolutely I see positive signs. I feel like everyone was trying to play for each other. Everyone was being positive on the field, communicating to me when I didn’t know the plays. I thought that was good.”