The 26-year-old former Castleford Tigers and Hull second-row forward has joined Leeds from Leigh Centurions on a contract until the end of this season and will make his debut in tonight’s final Betfred Super League game away to Salford Red Devils.
Leigh look set to miss out on a place in the Qualifiers and have begun trimming their squad, but Sinfield insisted Rhinos have not signed Thompson just because he was available.
Thompson has joined Leeds a week after they recruited front-row Dom Crosby on loan from Warrington and Sinfield said: “Jordan is a guy we’ve chased for a couple of weeks now.
“I feel on the outside looking in perhaps people will think vultures have been circling Leigh, certainly this week and certainly over the last 24 hours, but we first spoke to Leigh a couple of weeks ago about him.
“At that stage, he was unavailable because they were challenging for the top-four in the Championship.
“As that started to change a bit thankfully we were able to get him.
“We needed an extra second-rower or middle to provide that internal competition and, just like Dom Crosby, he comes very, very hungry and wanting to prove himself.
“He wants to help us get better and improve. The best teams, I feel, have great internal competition and we needed to add to that here.
“He certainly brings that and I am excited about seeing him play tonight.”
Rhinos will finish ninth whatever happens tonight and Salford are already confirmed in 11th place.
Sinfield has opted to rest several key players ahead of the Ladbrokes Challenge Cup semi-final against Warrington Wolves in nine days’ time.
“We are trying to make smart decisions,” said Sinfield.
“It’s about getting the balance right. We’ve got a big game coming up next week, but we also want to keep the momentum going. Every game is important. We need to improve every week.”