Rhinos began their Super-8s Qualifiers campaign by picking up only their second win in 10 games, but they had a scare when Toulouse hit back from 20-4 down to trail by only four points at the break.
The visitors missed a chance to go ahead early in the second half, but Rhinos eventually wore them down and five tries in the final 25 minutes got their fight against relegation off to a positive start.
“I’m pleased, I thought we played some really good stuff in patches,” Sinfield said. “We need to get those patches to be for longer periods, but I thought Toulouse had a real go.
“They are a dangerous side and when they came back at us at the end of that first half I did get a little bit concerned.
“The offloads they were playing and some of the long balls and kicks ricochetting left right and centre, they caused us some problems.
“Thankfully we were able to stick in there, especially at the start of the second half.
“It was a real challenge for our guys and it’s great to see us come through.
“I am really pleased to get a win, it has been a while.
“It’s nice to start this campaign off on the right foot, especially given the other results this weekend.”
Sinfield felt Rhinos had to be “more direct” in the second half.
“We felt it was almost turning into a game of touch and pass,” he added. “It was very loose and offloady and we felt we needed to grab control of that through a bit more dominance in our contact and also being very direct in our play.
“It took a little bit of time at the start of the second half, but I thought we managed that really well.
“Richie [Myler] on last plays in particular really put us in the right position and made it tough for them to come out of those corners.”
The opening round was a must-win game for Rhinos and Sinfield described it as a “big one for us”.
He predicted: “They will get some teams. They are a good side.”
An injury to winger Ryan Hall took some of the shine off Rhinos’ win.
He hobbled off with knee damage in the second half and Sinfield said: “He is walking around in the changing rooms.
“He is a bit of a freak, he tends to recover very quickly from what could be deemed really serious injuries.
“He’s smiling in there. We will get him scanned Monday morning, but at this stage I would probably say he is a doubt for next week.”
Rhinos visit London Broncos – who finished in second place in the Betfred Championship, above Toulouse on points difference – on Sunday.
Sinfield said: “We’re looking forward to it, going up against a really dangerous side.
“We will have a look at them this week, but it will be a tough one for us.
“We will prepare well this week and look forward to going down there.
“We are a good side. I think people have forgotten that.
“We played well in patches and the boys will take confidence from that.”
Stevie Ward, who missed Saturday’s game due to illness, could be available this weekend.
Meanwhile, Rhinos chief executive Gary Hetherington has dismissed rumours linking the club with Australian coach Anthony Griffin as “pure speculation”.
Griffin was sacked by NRL club Penrith Panthers last week.