Rhinos will go into Thursday’s derby at Castleford Tigers as First Utility Super League leaders, having won nine and drawn one of their 11 matches in the competition so far.
Leeds have conceded only 94 points and are showing some impressive signs on attack, with Ryan Hall having scored 11 tries in his last eight games.
Their last two matches have been a 30-12 Tetley’s Challenge Cup win over St Helens and the 28-12 defeat of Wigan Warriors in the league three days ago, but Sinfield denied Rhinos have done anything special yet.
“I wouldn’t say we are flying,” cautioned the long-servng captain. “We know where we’re at and there’s certainly some areas we need to improve in.
“We have got a couple of key people missing at the moment, but I thought Clarky (Chris Clarkson) did a great job for us on Friday, our pack really stood up again and our outside-backs kept doing what they’ve been doing all year.
“Wigan are a good side and they had a few missing as well, so we are not going to get carried away, at all. We recognise we are in for a real tough month.
“You look back at Easter and St Helens in the Cup and if you look at our fixtures this month, there’s some really difficult games and it is really going to test our squad.
“On Friday, our fans were fantastic again, they really got behind us and I hope they really enjoyed the game again.
“We were delighted with the two points, but we have been in this position before and come away with nothing, so it is important we keep working hard and keep showing the sort of attitude we’ve had this year.
“If we can continue with that, we will see what happens a bit later on.”
Sinfield insisted there are still improvements to be made. He added: “Very much so. We are all after the perfect game, whether we will ever get there I am not sure.
“There’s some things we would like to fix up, for example the tries we conceded near our line. We’ve not had that all year and that’s an area we will pay a lot of attention to over the next couple of weeks – especially going into Thursday.
“Defensively, we have made some massive strides, but it’s important to keep building on that and keep working hard for each other.”
Wigan made a number of breaks in last Friday’s game, but on most occasions Leeds’ defence scrambled back to snuff out the danger.
Sinfield reflected: “I think that is important. You realise you are in a fantastic team when people look after each other.
“People make mistakes, but other people cover back. That is something we have worked on and prided ourselves on this year.
“I think our front-up defence has improved, but certainly our scramble and our willingness to work for each other and our attitude and desire to cover up for each other has been key for us.
“It shows how close the group is and hopefully we can keep building. There were some huge efforts again on Friday. Our big men were fantastic again – JP (Jamie Peacock) and Kylie (Leuluai) were outstanding.
“It is really nice to put an 80 minutes together like that and come off knowing you have done a really good job against a quality team.”
Sinfield spent part of last Friday’s game at hooker, sharing the role with Chris Clarkson. Leeds’ regular acting-halves Rob Burrow and Paul Aiton are both on the casualty list and Sinfield said: “You can’t replace Rob or Paulie – it is an art form playing dummy-half.
“I have filled in that role from time to time, but the guys who’ve done it throughout their careers become magicians in there. Myself and Clarky are makeshift hookers, but it shows the spirit we have that guys are prepared to put their hand up and sacrifice themselves to go and do a particular role.”
Tigers will represent another huge challenge for Rhinos. They have been the surprise package this season and are genuine contenders for a top-four spot.
“The way they are playing, they have been absolutely outstanding,” Sinfield said. “What Daryl (coach Daryl Powell) has done there has transformed the pace.
“He’s an outstanding coach and I’ve had the pleasure of working with him on a few occasions.
“You can see what a fantastic coach he is and he is getting the best out of his players there.
“It is always a tough game for us, no matter what position Cas are in the league. We will expect a cracker, we expect Cas to be right at their very best and we’ll look forward to it.”